We have historically generated substantial cash from operations, which has enabled us to fund our growth while paying cash dividends and repurchasing stock. Cash and cash equivalents totaled $338.9 million and $348.6 million as of December 31, 2007 and 2006. Available-for-sale securities, consisting primarily of highly liquid investments, totaled $115.8 million and $124.8 million as of December 31, 2007 and 2006. Working capital at December 31, 2007 and 2006 was $631.5 million and $569.2 million.
Our first priority for our cash is growing the business, as we do require some working capital and a relatively small amount of capital expenditures to grow. We are continually looking for acquisitions to redeploy our cash, but those acquisitions must fit our culture and enhance our growth opportu- nities. If our cash balance continues to increase and there are no significant attractive acquisition opportunities, we expect to return more of the cash to our shareholders through future dividends and share repurchases.
cash flow from operating activities. We generated $308.4 million, $343.4 million, and $224.1 million of cash flow from operations in 2007, 2006, and 2005. During 2007, our cash flow from operations decreased 10.2% compared to a 21.5% increase in net income. The primary factor that caused this decrease in 2007 was the growth in our accounts receivables balance of 19.2% to $911.8 million in 2007 from $765.0 million in 2006, due to a slightly slower collection cycle from our customers.
cash flow from investing activities. We used $55.7 million, $81.2 million, and $86.7 million of cash flow for investing activities in 2007, 2006, and 2005. Our investing activities consist primarily of cash paid for acquisitions and our capital expenditures.
We used cash of $22.2 million, $39.7 million, and $60.2 million for acquisitions in 2007, 2006, and 2005. The amount paid in 2007 included $9.8 million related to the closing of one acquisition and $12.4 million related to earn-out payments and holdbacks from prior year acquisitions. As of De-cember 31, 2007, we have approximately $10.0 million of potential remaining earn-out payments and $1.1 million of potential remaining purchase price holdbacks expected to be paid in 2008.
We also used $43.7 million, $43.3 million, and $21.8 million of net capital expenditures in 2007, 2006, and 2005. We have invested in real estate in Chicago, Illinois, and Eden Prairie, Minnesota, related to office space in these cities, in which we have a high concentration of employees. We have spent $21.1 million, $22.5 million, and $5.7 million in 2007, 2006, and 2005 on these facilities. The remaining capital expenditures of $22.6 million, $20.8 million, and $16.1 million in 2007, 2006, and 2005 relate primarily to annual investments in information technology equipment to support our operating systems.
cash flow from financing activities. We used $262.1 million, $145.8 million, and $69.8 million of cash flow for financing activities in 2007, 2006, and 2005. This was primarily quarterly dividends and share repurchases.
We used $125.2 million, $90.8 million, and $51.5 million to pay cash dividends in 2007, 2006, and 2005, with the increase in 2007 due to a 38% increase in our quarterly dividend rate from $0.13 per share in 2006 to $0.18 per share in 2007.
We also used $167.3 million, $85.3 million, and $38.8 million of cash flow on share repurchases in 2007, 2006, and 2005, with the increase in 2007 due to a 70% increase in the number of shares repurchased and an increase in the stock price related to those purchases. We will continue to use share repurchases as a variable way to return excess capital to shareholders. Our Board of Directors has currently authorized a stock repurchase plan that has approximately 9,937,000 shares remaining for purchase.
We have 3.5 million euros available under a line of credit at an interest rate of Euribor plus 45 basis points (5.21% at December 31, 2007). This discretionary line of credit has no expiration date. Our credit agreement contains certain financial covenants, but does not restrict the payment of dividends. We were in compliance with all covenants of this agreement as of December 31, 2007.
Assuming no change in our current business plan, management believes that our available cash, together with expected future cash generated from operations and the amount available under our line of credit, will be sufficient to satisfy our anticipated needs for working capital, capital expenditures, and cash dividends for all future periods. We also believe we could obtain funds under additional lines of credit on short notice, if needed.
