Notes Receivable In 2014, we entered into a $3.0 million promissory note with a privately held company which was recorded at cost.
The interest rate on the promissory note is 8.0% per annum and is payable quarterly.
All unpaid principal and accrued interest on the promissory note is due and payable on the earlier of August 26, 2017, or upon default.5.
Commitments and Contingencies Operating Leases We lease various operating spaces in North America, Europe, Asia and Australia under non-cancelable operating lease arrangements that expire on various dates through 2024.
These arrangements require us to pay certain operating expenses, such as taxes, repairs, and insurance and contain renewal and escalation clauses.
We recognize rent expense under these arrangements on a straight-line basis over the term of the lease.
As of December 31, 2015, the aggregate future minimum payments under non-cancelable operating leases consist of the following (in thousands):
## Table 0 ##
ded December 31, 2015, 2014 and 2013, respectively.
Financing Obligation—Build-to-Suit Lease In August 2012, we executed a lease for a building then under construction in Santa Clara, California to serve as our headquarters.
The lease term is 120 months and commenced in August 2013.
Based on the terms of the lease agreement and due to our involvement in certain aspects of the construction such as our financial involvement in structural elements of asset construction, making decisions related to tenant improvement costs and purchasing insurance not reimbursable by the buyer-lessor (the Landlord), we were deemed the owner of the building (for accounting purposes only) during the construction period.
We continue to maintain involvement in the property post construction completion and lack transferability of the risks and rewards of ownership, due to our required maintenance of a $4.0 million letter of credit, in addition to our ability and option to sublease our portion of the leased building for fees substantially higher than our base rate.
Due to our continued involvement in the property and lack of transferability of related risks and rewards of ownership to the Landlord post construction, we account for the building and related improvements as a lease financing obligation.
Accordingly, as of December 31, 2015 and 2014, we have recorded assets of $53.4 million, representing the total costs of the building and improvements incurred, including the costs paid by the lessor (the legal owner of the building) and additional improvement costs paid by us, and a corresponding financing obligation of $42.5 million and $43.6 million, respectively.
As of December 31, 2015, $1.3 million and $41.2 million were recorded as short-term and long-term financing obligations, respectively.
Land lease expense under our lease financing obligation included in rent expense above, amounted to $1.3 million and $1.2 million for the years ended December 31, 2015 and 2014, respectively.
There was no land lease expense for the year ended December 31, 2013.
As of December 31, 2017, the aggregate future minimum payments under non-cancelable operating leases consist of the following (in thousands):
## Table 1 ##
Rent expense for all operating leases amounted to $9.4 million, $8.1 million and $5.4 million for the years ended December 31, 2017, 2016 and 2015, respectively.
Financing Obligation—Build-to-Suit Lease In August 2012, we executed a lease for a building then under construction in Santa Clara, California to serve as our headquarters.
The lease term is 120 months and commenced in August 2013.
Based on the terms of the lease agreement and due to our involvement in certain aspects of the construction, we were deemed the owner of the building (for accounting purposes only) during the construction period.
Upon completion of construction in 2013, we concluded that we had forms of continued economic involvement in the facility, and therefore did not meet with the provisions for sale-leaseback accounting.
We continue to maintain involvement in the property post construction and lack transferability of the risks and rewards of ownership, due to our required maintenance of a $4.0 million letter of credit, in addition to our ability and option to sublease our portion of the leased building for fees substantially higher than our base rate.
Therefore, the lease is accounted for as a financing obligation and lease payments will be attributed to (1) a reduction of the principal financing obligation; (2) imputed interest expense; and (3) land lease expense, representing an imputed cost to lease the underlying land of the building.
At the conclusion of the initial lease term, we will de-recognize both the net book values of the asset and the remaining financing obligation.
As of December 31, 2017 and 2016, we have recorded assets of $53.4 million, representing the total costs of the building and improvements incurred, including the costs paid by the lessor (the legal owner of the building) and additional improvement costs paid by us, and a corresponding financing obligation of $39.6 million and $41.2 million, respectively.
As of December 31, 2017, $1.9 million and $37.7 million were recorded as short-term and long-term financing obligations, respectively.
Land lease expense under our lease financing obligation amounted to $1.3 million for each of the years ended December 31, 2017, 2016 and 2015 respectively.
As of December 31, 2017, the future minimum payments due under the lease financing obligation were as follows (in thousands):
## Table 2 ##
Purchase Commitments We outsource most of our manufacturing and supply chain management operations to third-party contract manufacturers, who procure components and assemble products on our behalf based on our forecasts in order to reduce manufacturing lead times and ensure adequate component supply.
We issue purchase orders to our contract manufacturers for finished product and a significant portion of these orders consist of firm non-cancellable commitments.
In addition, we purchase strategic component inventory from certain suppliers under purchase commitments that in some cases are non-cancellable, including integrated circuits, which are consigned to our contract manufacturers.
As of December 31, 2017, we had non-cancellable purchase commitments of $195.1 million, of which $147.9 million was to our contract manufacturers and suppliers.
In addition, we have provided deposits to secure our obligations to purchase inventory.
We had $36.9 million and $63.1 million in deposits as of December 31, 2017 and 2016, respectively.
These deposits are classified in 'Prepaid expenses and other current assets' and 'Other assets' in our accompanying consolidated balance sheets.
Guarantees We have entered into agreements with some of our direct customers and channel partners that contain indemnification provisions relating to potential situations where claims could be alleged that our products infringe the intellectual property rights of a third party.
We have at our option and expense the ability to repair any infringement, replace product with a non-infringing equivalent-in-function product or refund our customers all or a portion of the value of the product.
Other guarantees or indemnification agreements include guarantees of product and service performance and standby letters of credit for leased facilities and corporate credit cards.
We have not recorded a liability related to these indemnification and guarantee provisions and our guarantee and indemnification arrangements have not had any significant impact on our consolidated financial statements to date.
Legal Proceedings OptumSoft, Inc.  Matters On April 4, 2014, OptumSoft filed a lawsuit against us in the Superior Court of California, Santa Clara County titled OptumSoft, Inc.  v.  Arista Networks, Inc. , in which it asserts (i) ownership of certain components of our EOS network operating system pursuant to the terms of a 2004 agreement between the companies; and (ii) breaches of certain confidentiality and use restrictions in that agreement.
Under the terms of the 2004 agreement, OptumSoft provided us with a non-exclusive, irrevocable, royalty-free license to software delivered by OptumSoft comprising a software tool used to develop certain components of EOS and a runtime library that is incorporated
Revenue by Geography (in thousands, except percentages)
## Table 3 ##
Revenue We generate revenue primarily from sales of our products.
We also derive a portion of our revenue from sales of PCS, which is typically purchased in conjunction with our products, and subsequent renewals of those contracts.
We expect our revenue may vary from period to period based on, among other things, the timing and size of orders, the delivery and acceptance of products, and the impact of significant transactions.
In addition, while we expect our revenue to continue to grow in absolute dollars on a year-over-year basis, our revenue growth rates are expected to decline as our business scales.
Product revenue increased $408.3 million, or 28.5%, in the year ended December 31, 2018 compared to 2017.
The increase was primarily driven by sales to our existing customers as they continued to expand and upgrade their cloud networks.
In addition, our newer switch products have continued to gain market acceptance, which has contributed to our revenue growth.
Service revenue increased $96.9 million, or 45.4%, in the year ended December 31, 2018 compared to 2017 as a result of continued growth in initial and renewal support contracts as our customer installed base has continued to expand.
We continue to experience pricing pressure on our products and services due to competition, but demand for our products and growth in our installed base has more than offset this pricing pressure during the period.
Cost of Revenue and Gross Margin Cost of revenue primarily consists of amounts paid for inventory to our third-party contract manufacturers and merchant silicon vendors, overhead costs in our manufacturing operations department, and other manufacturing-related costs associated with manufacturing our products and managing our inventory.
Cost of revenue increased $193.6 million or 33.1% for the year ended December 31, 2018 compared to 2017.
The increase in cost of revenue was primarily due to the corresponding increases in product revenues.
We expect our cost of product revenue to continue to increase as our product revenue increases.
Cost of providing PCS and other services consists primarily of personnel costs for our global customer support organization.
Gross margin, or gross profit as a percentage of revenue, has been and will continue to be affected by a variety of factors, including sales to large end customers who generally receive lower pricing, manufacturingrelated costs including costs associated with supply chain sourcing activities, merchant silicon costs, the mix of products sold, and excess/obsolete inventory write-downs, including charges for excess/obsolete component inventory held by our contract manufacturers.
Gross margin decreased from 64.5% to 63.8% for the year ended December 31, 2018 compared to 2017.
The decrease in gross margin was primarily driven by a decrease in product margins due to customer mix, partially offset by reduced inventory-related charges and an improved service margins due to a relatively fixed services cost base and growing service revenues.
We expect our gross margins to fluctuate over time, depending on the factors described above.
Operating Expenses (in thousands, except percentages) Our operating expenses consist of research and development, sales and marketing, general and administrative expenses, and legal settlement expense.
The largest component of our operating expenses is personnel costs.
Personnel costs consist of wages, benefits, bonuses and, with respect to sales and marketing expenses, sales commissions.
Personnel costs also include stock-based compensation and travel expenses.
We
expect operating expenses to continue to increase in absolute dollars in the near term as we continue to invest in the growth of our business.
## Table 4 ##
* Not meaningful.
Research and development.
Research and development expenses consist primarily of personnel costs, prototype expenses, third-party engineering and contractor support costs, and an allocated portion of facility and IT costs including depreciation.
Our research and development efforts are focused on maintaining and developing additional functionality for our existing products and on new product development, including new releases and upgrades to our EOS software and applications.
We expect our research and development expenses to increase in absolute dollars as we continue to invest heavily in software development in order to expand the capabilities of our cloud networking platform, introduce new products and features and build upon our technology leadership.
Research and development expenses increased $92.9 million, or 26.6%, for the year ended December 31, 2018 compared to 2017.
The increase was primarily due to a $48.9 million increase in personnel costs, including corporate bonuses and stock-based compensation, driven primarily by headcount growth from our normal hiring process and from the two acquisitions we completed in the third quarter of 2018, and a $24.7 million increase in new product introduction costs, driven by additional development projects.
In addition, facility and IT costs increased by $9.5 million due to increased IT services, headcount growth and additional costs associated with our acquired businesses.
Sales and marketing.
Sales and marketing expenses consist primarily of personnel costs, marketing and promotional activities, and an allocated portion of facility and IT costs including depreciation.
We expect our sales and marketing expenses to increase in absolute dollars as we continue to expand our sales and marketing efforts worldwide.
Sales and marketing expenses increased $32.0 million, or 20.7% for the year ended December 31, 2018 compared to 2017.
The increase primarily included a $28.0 million increase in personnel costs, which was driven by increased headcount as well as higher sales volumes, resulting in increased compensation costs, including commissions and stock-based compensation.
General and administrative.
General and administrative expenses consist primarily of Cisco and OptumSoft litigation related expenses, personnel costs, professional services fees, and an allocated portion of facility and IT costs including depreciation.
General and administrative personnel costs include those for our executive, finance, human resources and legal functions.
Our professional services fees are primarily due to external legal, accounting, and tax services.
General and administrative expenses decreased $21.4 million, or 24.6%, for the year ended December 31, 2018 compared to 2017.
The decrease included a $33.8 million decrease that was primarily related to a reduced level of litigation activities and a decrease in bond costs as a result of the settlement of the Cisco litigation in August 2018.
The decrease was partially offset by $3.5 million of acquisition-related expenses incurred in 2018,

Tables referenced above, in order (Table 0 first):
<table><tr><td>2016</td><td>$6,306</td></tr><tr><td>2017</td><td>6,678</td></tr><tr><td>2018</td><td>6,260</td></tr><tr><td>2019</td><td>5,809</td></tr><tr><td>2020</td><td>5,580</td></tr><tr><td>Thereafter</td><td>21,450</td></tr><tr><td>Total minimum future lease payments</td><td>$52,083</td></tr></table>
<table><tr><td>2018</td><td>$9,127</td></tr><tr><td>2019</td><td>8,336</td></tr><tr><td>2020</td><td>8,350</td></tr><tr><td>2021</td><td>7,741</td></tr><tr><td>2022</td><td>7,577</td></tr><tr><td>Thereafter</td><td>9,873</td></tr><tr><td>Total minimum future lease payments</td><td>$51,004</td></tr></table>
<table><tr><td>2018</td><td>$6,113</td></tr><tr><td>2019</td><td>6,293</td></tr><tr><td>2020</td><td>6,477</td></tr><tr><td>2021</td><td>6,674</td></tr><tr><td>2022</td><td>6,871</td></tr><tr><td>Thereafter</td><td>5,264</td></tr><tr><td>Total payments</td><td>37,692</td></tr><tr><td>Less: interest and land lease expense</td><td>-21,730</td></tr><tr><td>Total payments under facility financing obligations</td><td>15,962</td></tr><tr><td>Property reverting to landlord</td><td>23,630</td></tr><tr><td>Present value of obligation</td><td>39,592</td></tr><tr><td>Less: current portion</td><td>-1,919</td></tr><tr><td>Lease financing obligations, non-current</td><td>$37,673</td></tr></table>
<table><tr><td></td><td colspan="4">Year Ended December 31,</td></tr><tr><td></td><td>2018</td><td>% of Total</td><td>2017</td><td>% of Total</td></tr><tr><td>Americas</td><td>$1,550,453</td><td>72.1%</td><td>$1,192,289</td><td>72.4%</td></tr><tr><td>Europe, Middle East and Africa</td><td>414,069</td><td>19.2</td><td>299,547</td><td>18.2</td></tr><tr><td>Asia-Pacific</td><td>186,847</td><td>8.7</td><td>154,350</td><td>9.4</td></tr><tr><td>Total revenue</td><td>$2,151,369</td><td>100.0%</td><td>$1,646,186</td><td>100.0%</td></tr></table>
<table><tr><td></td><td colspan="4">Year Ended December 31,</td><td colspan="2"></td></tr><tr><td></td><td colspan="2">2018</td><td colspan="2">2017</td><td colspan="2">Change in</td></tr><tr><td></td><td>$</td><td>% ofRevenue</td><td>$</td><td>% ofRevenue</td><td>$</td><td>%</td></tr><tr><td>Operating expenses:</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Research and development</td><td>$442,468</td><td>20.6%</td><td>$349,594</td><td>21.2%</td><td>$92,874</td><td>26.6%</td></tr><tr><td>Sales and marketing</td><td>187,142</td><td>8.7</td><td>155,105</td><td>9.4</td><td>32,037</td><td>20.7</td></tr><tr><td>General and administrative</td><td>65,420</td><td>3.0</td><td>86,798</td><td>5.3</td><td>-21,378</td><td>-24.6</td></tr><tr><td>Legal settlement</td><td>405,000</td><td>18.8</td><td>—</td><td>—</td><td>405,000</td><td>*</td></tr><tr><td>Total operating expenses</td><td>$1,100,030</td><td>51.1%</td><td>$591,497</td><td>35.9%</td><td>$508,533</td><td>86.0%</td></tr></table>

Question: How many subterms of Operating expenses keeps increasing between 2018 and 2017?
Answer: 3