We recently determined to market Medicare related health insurance products using our ecommerce platform, including Medicare Advantage, Medicare Supplement and Medicare Part D prescription drug plans. We plan to offer Medicare products to Medicare eligible individuals, who are predominately senior citizens over the age of 65. We determined to enter into the Medicare product market, because we believe there is an increasing number of individuals becoming eligible for Medicare and that Medicare eligible individuals are increasingly using the Internet to shop for health insurance products that supplement Medicare. We also believe that, on average, member retention rates and the commissions that health insurance carriers pay in connection with the sale of Medicare products compare favorably to the member retention rates and commissions we receive in connection with our sale of individual and family health insurance. The success of our entry into the market for Medicare products will depend upon our ability to enter into and maintain relationships with health insurance carriers on favorable economic terms to market these products on our ecommerce platform. As with our non-Medicare products, our revenue related to the marketing and sale of Medicare products is expected to consist predominantly of commissions paid to us from these health insurance carriers. We expect to invest approximately $3 million, primarily in the customer care and enrollment and technology and content areas, in 2010 to support and grow our Medicare business.
(2) IFP applications submitted on eHealth’s website during the period. Applications are counted as submitted when the applicant completes the application and clicks the submit button on our website and submits the application to us. The applicant generally has additional actions to take before the application will be reviewed by the insurance carrier, such as providing additional information, providing an electronic signature, and in some cases, providing a method for payment. In addition, an applicant may submit more than one application. We include applications for IFP products for which we receive commissions as well as other forms of payment. We define our “IFP” offerings as major medical individual and family health insurance plans, which does not include small business, short-term major medical, stand-alone dental, life or student health insurance product offerings.
2009 compared to 2008-Commission revenue increased $18.4 million, or 18%, in 2009 compared to 2008, primarily due to an increase in our membership. Our estimated membership increased approximately 17% to 728,000 at December 31, 2009 from 621,100 at December 31, 2008. Estimated membership at December 31, 2009 includes approximately 20,000 members, net of estimated cancellations, transferred from Health Benefits Direct Corporation, or HBDC, during 2009. Sponsorship, licensing and other revenue increased $4.8 million, or 44%, in 2009 compared to 2008, primarily due to an increase of $2.6 million from licensing arrangements related to our technology and an increase of $1.7 million related to sales of carrier sponsorship advertising on our website.
2009 compared to 2008- Marketing and advertising expenses increased $11.8 million, or 28%, in 2009 compared to 2008. This was primarily due to an increase in our online advertising expenses of $7.1 million resulting from an increase in paid keyword search advertising costs on Internet search engines, as the cost and number of click-throughs from the online advertising channel increased. Marketing partner expenses increased $1.9 million due to an increase in the costs per application and the growth in the number of applications submitted on our website through the marketing partner channel during 2009 compared to 2008. Additionally, compensation and benefits costs attributable to marketing and advertising personnel increased $1.6 million associated with an increase in marketing and advertising personnel. We also experienced a decline in the rate at which individuals coming to our ecommerce platform through the direct, marketing partner and online advertising member acquisition channels submitted health insurance applications, along with a decline in the average number of individuals applying for health insurance per application submitted through the direct, marketing partner and online advertising member acquisition channels. As a result, our acquisition cost per member, measured as total marketing and advertising expenses for the year divided by the number of individuals included on applications for individual and family health insurance submitted during the year, increased 15% to $70.82 in 2009 from $61.68 in 2008. As a percentage of total revenue, total marketing and advertising expenses increased to 40% in 2009 from 38% in 2008.
2008 compared to 2007-Customer care and enrollment expenses increased $2.2 million, or 18%, in 2008 compared to 2007, primarily due to an increase of $1.3 million in compensation and benefit costs associated with an increase in personnel servicing health insurance applications submitted through our website. As a percentage of total revenue, customer care and enrollment expenses decreased to 13% in 2008 from 14% in 2007 as a result of economies of scale achieved by our customer care and enrollment operations in 2007.
Interest and other income, net, primarily consists of interest income earned on our invested cash, cash equivalents and marketable securities balances, partially offset by administrative bank fees, investment management fees and interest expense on our capital lease obligations.
(4) On January 1, 2007, 2008 and 2009, the number of shares authorized for issuance under the 2006 Plan was automatically increased pursuant to the terms of the 2006 Plan by 869,957 shares, 987,473 shares and 1,001,637 shares, respectively.
tax rate primarily due to the releases of our valuation allowance against deferred tax assets in that year. The net valuation allowance decreased by $18.9 million during the year ended December 31, 2007, and increased $0.1 million in each of the years ended December 31, 2008 and 2009.
For each of the years ended December 31, 2007, 2008 and 2009, we had securities outstanding that could potentially dilute earnings per share, but the shares from the assumed conversion or exercise of these securities were excluded in the computation of diluted net income per share as their effect would have been anti-dilutive.