transactions during the year ended December 31, 2019 was $189.5 million, and the maximum amount outstanding at any month end was $274.5 million. To manage our cash position more efficiently, we may enter into repurchase agreements with unaffiliated financial institutions. We generally use repurchase agreements as a means to finance the purchase of invested assets or for short-term general business purposes until projected cash flows become available from our operations or existing investments. We had no repurchase agreements outstanding at December 31, 2019, nor did we utilize any repurchase agreements during 2019. Our use of repurchase agreements and securities lending agreements can fluctuate during any given period and will depend on our liquidity position, the availability of long-term investments that meet our purchasing criteria, and our general business needs. Certain of our U.S. insurance subsidiaries are members of regional Federal Home Loan Banks (FHLB). As of December 31, 2019, we owned $18.5 million of FHLB common stock and had no outstanding advances from the regional FHLBs. See Note 3 of the "Notes to Consolidated Financial Statements" contained herein in Item 8 for additional information. Consolidated Cash Flows Year Ended December 31 2019 2018 2017 Net Cash Provided by Operating Activities $ 1,741.6  $ 1,536.5  $ 1,164.1  Net Cash Used by Investing Activities (1,393.5) (930.1) (499.3) Net Cash Used by Financing Activities (358.0) (589.8) (687.8) Net Change in Cash and Bank Deposits $ (9.9) $ 16.6  $ (23.0) (in millions of dollars) Operating Cash Flows Investing Cash Flows See Notes 3 and 13 of the "Notes to Consolidated Financial Statements" contained herein in Item 8 for further information. Investing cash inflows consist primarily of the proceeds from the sales and maturities of investments. Investing cash outflows consist primarily of payments for purchases of investments. Our investment strategy is to match the cash flows and durations of our assets with the cash flows and durations of our liabilities to meet the funding requirements of our business. When market opportunities arise, we may sell selected securities and reinvest the proceeds to improve the yield and credit quality of our portfolio. We may at times also sell selected securities and reinvest the proceeds to improve the duration matching of our assets and liabilities and/or re-balance our portfolio. As a result, sales before maturity may vary from period to period. The sale and purchase of short-term investments is influenced by proceeds received from issuance of debt, our securities lending program, and by the amount of cash which is at times held in short-term investments to facilitate the availability of cash to fund the purchase of appropriate long-term investments, repay maturing debt, and/or to fund our capital deployment program. Our cash flows for 2018 include cash outflows, net of cash acquired, of $145.4 million related to all of our acquisitions during the year. The variance in the change in insurance reserves and liabilities to reconcile net income to net cash provided by operating activities as reported in our consolidated statements of cash flows for 2018 was due primarily to the 2018 reserve increase for our long-term care line of business. Operating cash flows are primarily attributable to the receipt of premium and investment income, offset by payments of claims, commissions, expenses, and income taxes. Premium income growth is dependent not only on new sales, but on policy renewals and growth of existing business, renewal price increases, and persistency. Investment income growth is dependent on the growth in the underlying assets supporting our insurance reserves and capital and on the earned yield. The level of commissions and operating expenses is attributable to the level of sales and the first year acquisition expenses associated with new business as well as the maintenance of existing business. The level of paid claims is affected partially by the growth and aging of the block of business and also by the general economy, as previously discussed in the operating results by segment. 87