LIQUIDITY AND CAPITAL RESOURCES
Our primary source of cash is from the sale of our software and related services. Our primary use of cash is payment of our operating costs, which consist primarily of employee-related expenses, such as compensation and benefits, as well as general operating expenses for marketing, facilities and overhead costs. In addition to operating expenses, we also use cash to fund our stock repurchase program and invest in our growth initiatives, which include acquisitions of products, technology and businesses. See further discussion of these items below.
At January 31, 2019, our principal sources of liquidity were cash, cash equivalents, and marketable securities totaling $953.6 million and net accounts receivable of $474.3 million
On December 17, 2018, Autodesk entered into a new Credit Agreement (the “Credit Agreement”) for an unsecured revolving loan facility in the aggregate principal amount of $650.0 million, with an option to request increases in the amount of the credit facility by up to an additional $350.0 million. The Credit Agreement replaced and terminated our $400.0 million Amended and Restated Credit Agreement. The maturity date on the line of credit facility is December 2023. At January 31, 2019, Autodesk had no outstanding borrowings on this line of credit. As of March 25, 2019, we have no amounts outstanding under the credit facility. See Part II, Item 8, Note 8, "Borrowing Arrangements," in the Notes to Consolidated Financial Statements for further discussion on our covenant requirements. If we are unable to remain in compliance with the covenants, we will not be able to draw on our credit facility.
On December 17, 2018, we also entered into a Term Loan Agreement (the “Term Loan Agreement”) which provided for a delayed draw term loan facility in the aggregate principal amount of $500.0 million. On December 19, 2018, we borrowed a $500.0 million term loan under the Term Loan Agreement in connection with the acquisition of PlanGrid. See Part II, Item 8,Note 8, "Borrowing Arrangements," in the Notes to Consolidated Financial Statements for further discussion on the Term Loan Agreement terms and Part II, Item 8, Note 6, "Acquisitions" for further discussion on the PlanGrid acquisition.
In addition to the term loan, as of January 31, 2019, we have $1.6 billion aggregate principal amount of Notes outstanding. See Part II, Item 8, Note 8, "Borrowing Arrangements," in the Notes to Consolidated Financial Statements for further discussion.
Our cash and cash equivalents are held by diversified financial institutions globally. Our primary commercial banking relationship is with Citigroup and its global affiliates. In addition, Citibank N.A., an affiliate of Citigroup, is one of the lead lenders and agent in the syndicate of our $650.0 million line of credit.
Long-term cash requirements for items other than normal operating expenses are anticipated for the following: repayment of debt; common stock repurchases; the acquisition of businesses, software products, or technologies complementary to our business; and capital expenditures, including the purchase and implementation of internal-use software applications
Our cash, cash equivalents, and marketable securities balances are concentrated in a few locations around the world, with substantial amounts held outside of the United States. As of January 31, 2019, approximately 52% of our total cash or cash equivalents and marketable securities are located in foreign jurisdictions and that percentage will fluctuate subject to business needs. There are several factors that can impact our ability to utilize foreign cash balances, such as foreign exchange restrictions, foreign regulatory restrictions or adverse tax costs. The Tax Act includes a mandatory one-time tax on accumulated earnings of foreign subsidiaries and generally eliminates U.S. taxes on foreign subsidiary distributions in future periods. As a result, earnings in foreign jurisdictions are generally available for distribution to the U.S. with little to no incremental U.S. taxes. We regularly review our capital structure and consider a variety of potential financing alternatives and planning strategies to ensure we have the proper liquidity available in the locations in which it is needed. We expect to meet our liquidity needs through a combination of current cash balances, ongoing cash flows, and external borrowings.
Cash from operations could also be affected by various risks and uncertainties, including, but not limited to the risks detailed in Part I, Item 1A titled “Risk Factors.” However, based on our current business plan and revenue prospects, we believe that our existing balances, our anticipated cash flows from operations and our available credit facility will be sufficient to meet our working capital and operating resource expenditure requirements for at least the next 12 months.
Our revenue, earnings, cash flows, receivables, and payables are subject to fluctuations due to changes in foreign currency exchange rates, for which we have put in place foreign currency contracts as part of our risk management strategy. See Part II, Item 7A, “Quantitative and Qualitative Disclosures about Market Risk” for further discussion.
Net cash provided by operating activities of $377.1 million for fiscal 2019 consisted of $371.8 million of non-cash expenses, including stock-based compensation expense, restructuring charges, net, depreciation, amortization and accretion expense, offsetting our net loss of $80.8 million, and included $86.1 million of cash flow provided by changes in operating assets and liabilities.
The primary working capital source of cash was an increase in deferred revenue from $1,955.1 million as of January 31, 2018, to $2,091.4 million as of January 31, 2019. The primary working capital uses of cash were decreases in accounts payable and other accrued liabilities.
Net cash used in investing activities was $710.4 million for fiscal 2019 and was primarily due to acquisitions, net of cash acquired and purchases of marketable securities. These cash outflows were partially offset by sales and maturities of marketable securities.
At January 31, 2019, our short-term investment portfolio had an estimated fair value of $67.6 million and a cost basis of $62.8 million. The portfolio fair value consisted of $60.3 million of trading securities that were invested in a defined set of mutual funds as directed by the participants in our Deferred Compensation Plan (see Note 7, “Deferred Compensation,” in the Notes to Consolidated Financial Statements for further discussion) and $7.3 million invested in other available-for-sale shortterm securities.
Net cash provided by financing activities was $151.9 million in fiscal 2019 and was primarily due to proceeds from debt issuance, net of discount and proceeds from issuance of stock. These cash inflows were partially offset by repurchases of our common stock and taxes paid related to net share settlement of equity awards.
Table:
 |  | Fiscal year ended January 31, | 
(in millions) | 2019 | 2018 | 2017
Net cash provided by operating activities | $377.1 | $0.9 | $169.7
Net cash (used in) provided by investing activities | (710.4) | 506.4 | 272.0
Net cash provided by (used in) financing activities | 151.9 | (656.6) | (578.3)


Question: How much is the increase in primary working capital use of cash from 2018 to 2019?
Answer: 136.3
Calculation: 2,091.4-1,955.1