(5) Total revenue (from all sources) recognized during the period from the consolidated statements of income.
After we have estimated membership for a period, we may receive information from health insurance carriers that would have impacted the estimate if we had received the information prior to the date of estimation. We may receive commission payments or other information that indicates that a member who was not included in our estimates for a prior period was in fact an active member at that time, or that a member who was included in our estimates was in fact not an active member of ours. For instance, we reconcile information carriers provide to us and may determine that we were not historically paid commissions owed to us, which would cause us to have underestimated our membership. Conversely, carriers may require us to return commission payments paid in a prior period due to policy cancellations for members we previously estimated as being active. We reflect updated information regarding our membership in the membership estimate for the current period that we are estimating, if applicable. As a result of the delay in our receipt of information from insurance carriers, actual trends in our membership are most discernable over periods longer than from one quarter to the next. In addition, and as a result of the delay we experience in receiving information about our membership, it is difficult for us to determine with any certainty the impact of current economic conditions on our membership retention.
Substantially all revenue for all years presented was generated from customers located in the United States. The following carriers (including carriers owned by them) represented 10% or more of our total revenue for the years ended December 31, 2007, 2008 and 2009:
2009-Net cash provided by investing activities of $30.7 million during 2009 was primarily attributable to maturities and sales of marketable securities of $73.9 million, partially offset by purchases of marketable securities of $40.6 million, capital expenditures of $1.4 million and initial consideration of $1.3 million paid to HBDC in connection with customer transition and marketing agreements.
2008-Net cash used in investing activities of $18.7 million during the year ended December 31, 2008 was primarily attributable to purchases of marketable securities of $85.7 million and capital expenditures of $2.5 million, partially offset by sales and maturities of marketable securities of $10.1 million and $59.3 million, respectively. Capital expenditures in 2008 were impacted by a project relating to the expansion of our data center operations.
Use of Estimates-The preparation of consolidated financial statements and related disclosures in conformity with U.S. GAAP requires management to make estimates, judgments and assumptions that affect the amounts reported and disclosed in the consolidated financial statements and accompanying notes. On an ongoing basis, we evaluate our estimates, including those related to, but not limited to, the useful lives of long-lived assets including property and equipment, fair value of investments, fair value of intangible assets, allowances for commission forfeitures payable to carriers, valuation allowance for deferred income taxes, provision for income taxes, our assessment whether internal use software and website development costs will result in additional functionality, estimates relating to the amortization of the initial consideration paid to Health Benefits Direct Corporation which is being recognized as cost of revenue-sharing expense and the assumptions used in determining stock-based compensation. We base our estimates of the carrying value of certain assets and liabilities on historical experience and on various other assumptions that we believe to be reasonable. Actual results may differ from these estimates.
All of our marketable securities are classified as available-for-sale. Marketable securities are carried at their fair value, based on quoted market prices or other available information, with unrealized gains and losses, net of
The following table presents information about our financial assets (cash equivalents and marketable securities) that are re-measured and reported at fair value on a recurring basis as of December 31, 2009, and indicates the fair value hierarchy of the valuation techniques we utilized to determine such fair value (in thousands):
Stock Plans-Our 2006 Equity Incentive Plan (the “2006 Plan”) became effective in October 2006. As of December 31, 2009, we had 3,180,800 shares of our common stock available for future grants under the 2006 Plan. In general, if options or shares awarded under the 2006 Plan are forfeited or repurchased, those options or shares will again become available for grant under the 2006 Plan. In addition, on January 1 of each year, the number of shares available for future grant under the 2006 Plan will automatically increase by the lowest of (a) 1,500,000 shares, (b) 4% of the total number of shares of our common stock then outstanding or (c) a lower number determined by our board of directors or its compensation committee. As of January 1, 2007, 2008, 2009 and 2010, shares reserved under the 2006 Plan automatically increased by 869,957 shares, 987,473 shares, 1,001,637 shares and 936,669 shares, respectively, which equaled 4% of the total number of shares of our common stock then outstanding. Employees, non-employee members of our board of directors and consultants of our company are eligible to participate in our 2006 Plan. The 2006 Plan requires that the exercise price of stock options and stock appreciation rights awarded shall in no event be less than 100% of the fair market value of a share of common stock on the date of grant.