ITEM 6. SELECTED FINANCIAL DATA
The selected consolidated statements of operations data for the years ended December 31, 2019, 2018 and 2017 and the selected consolidated balance sheet data as of December 31, 2019 and 2018 are derived from our audited consolidated financial statements included elsewhere in this Annual Report. The selected consolidated statements of operations data for the years ended December 31, 2016 and 2015 and the selected consolidated balance sheet data as of December 31, 2017, 2016 and 2015 are derived from our audited consolidated financial statements not included in this Annual Report. Our historical results are not necessarily indicative of the results to be expected in the future. The selected financial data should be read together with Item 7. "Management’s Discussion and Analysis of Financial Condition and Results of Operations" and in conjunction with our consolidated financial statements, related notes, and other financial information included elsewhere in this Annual Report. The following tables set forth our selected consolidated financial and other data for the years ended and as of December 31, 2019, 2018, 2017, 2016 and 2015 (in thousands, except share and per share data).
Information about prior period acquisitions that may affect the comparability of the selected financial information presented below is included in Item 1. Business. Information about the $28.0 million expense recorded in general and administrative expense in 2018, which relates to the agreement reached to settle the legal matter alleging violations of the Telephone Consumer Protection Act, or TCPA, and may affect the comparability of the selected financial information presented below, is disclosed in Item 3. “Legal Proceedings.” Information about the $1.7 million of interest recorded within interest income and the $6.9 million of gain recorded within other income, net, in 2019, which relates to promissory note proceeds received from one of our hardware suppliers and proceeds from an acquired promissory note, and may affect the comparability of the selected financial information presented below, is disclosed in Item 7. "Management’s Discussion and Analysis of Financial Condition and Results of Operations."
Certain previously reported amounts in the consolidated statements of operations for the years ended December 31, 2018, 2017, 2016 and 2015 have been reclassified to conform to our current presentation to reflect interest income as a separate line item, which was previously included in other income, net.
(3) We measure our SaaS and license revenue renewal rate on a trailing 12-month basis by dividing (a) the total SaaS and license revenue recognized during the trailing 12-month period from subscribers on our Alarm.com platform who were subscribers on the first day of the period, by (b) total SaaS and license revenue we would have recognized during the period from those same subscribers assuming no terminations, or service level upgrades or downgrades. The SaaS and license revenue renewal rate represents both residential and commercial properties. Our SaaS and license revenue renewal rate is expressed as an annualized percentage. Our service provider partners, who resell our services to our subscribers, have indicated that they typically have three to five-year service contracts with our subscribers. Our SaaS and license revenue renewal rate is calculated across our entire subscriber base on the Alarm.com platform, including subscribers whose contract with their service provider reached the end of its contractual term during the measurement period, as well as subscribers whose contract with their service provider has not reached the end of its contractual term during the measurement period, and is not intended to estimate the rate at which our subscribers renew their contracts with our service provider partners. We believe that our SaaS and license revenue renewal rate allows us to measure our ability to retain and grow our SaaS and license revenue and serves as an indicator of the lifetime value of our subscriber base.
(4) We define Adjusted EBITDA as our net income before interest expense, interest income, other income, net, provision for / (benefit from) income taxes, amortization and depreciation expense, stock-based compensation expense, acquisition-related expense and legal costs and settlement fees incurred in connection with non-ordinary course litigation and other disputes, particularly costs involved in ongoing intellectual property litigation. We do not consider these items to be indicative of our core operating performance. The non-cash items include amortization and depreciation expense and stock-based compensation expense. Included in 2015 stock-based compensation expense is $0.8 million related to the repurchase of an employee's stock awards. We do not adjust for ordinary course legal expenses resulting from maintaining and enforcing our intellectual property portfolio and license agreements. Adjusted EBITDA is not a measure calculated in accordance with accounting principles generally accepted in the United States, or GAAP. See the table below for a reconciliation of Adjusted EBITDA to net income, the most directly comparable financial measure calculated and presented in accordance with GAAP.
Table:
 |  |  | Year Ended December 31, |  | 
 | 2019 | 2018 | 2017 | 2016 | 2015
Other Financial and Operating Data: |  |  |  |  | 
SaaS and license revenue renewal rate(3) | 94% | 93% | 93% | 94% | 93%
Adjusted EBITDA(4) | $108,307 | $93,081 | $71,628 | $49,034 | $34,370


Question: How many years did the adjusted EBITDA exceed $50,000 thousand?
Answer: 3
Calculation: 2019##2018##2017