we prepare estimates of research and development costs for projects in clinical development , which include direct costs and allocations of certain costs such as indirect labor , non-cash compensation expense , and manufacturing and other costs related to activities that benefit multiple projects , and , under our collaboration with bayer healthcare , the portion of bayer healthcare 2019s vegf trap-eye development expenses that we are obligated to reimburse . our estimates of research and development costs for clinical development programs are shown below : project costs year ended december 31 , increase ( decrease ) ( in millions ) 2009 2008 .
what was the percentage change in research and development costs related to vegf trap-eye from 2008 to 2009?
for the reasons described above in results of operations for the years ended december 31 , 2010 and 2009 , under the caption 201cresearch and development expenses 201d , and due to the variability in the costs necessary to develop a pharmaceutical product and the uncertainties related to future indications to be studied , the estimated cost and scope of the projects , and our ultimate ability to obtain governmental approval for commercialization , accurate and meaningful estimates of the total cost to bring our product candidates to market are not available . similarly , we are currently unable to reasonably estimate if our product candidates will generate material product revenues and net cash inflows . in 2008 , we received fda approval for arcalyst ae for the treatment of caps , a group of rare , inherited auto-inflammatory diseases that affect a very small group of people . we currently do not expect to generate material product revenues and net cash inflows from the sale of arcalyst ae for the treatment of caps . selling , general , and administrative expenses selling , general , and administrative expenses increased to $ 52.9 million in 2009 from $ 48.9 million in 2008 . in 2009 , we incurred ( i ) higher compensation expense , ( ii ) higher patent-related costs , ( iii ) higher facility-related costs due primarily to increases in administrative headcount , and ( iv ) higher patient assistance costs related to arcalyst ae . these increases were partly offset by ( i ) lower marketing costs related to arcalyst ae , ( ii ) a decrease in administrative recruitment costs , and ( iii ) lower professional fees related to various corporate matters . cost of goods sold during 2008 , we began recognizing revenue and cost of goods sold from net product sales of arcalyst ae . cost of goods sold in 2009 and 2008 was $ 1.7 million and $ 0.9 million , respectively , and consisted primarily of royalties and other period costs related to arcalyst ae commercial supplies . in 2009 and 2008 , arcalyst ae shipments to our customers consisted of supplies of inventory manufactured and expensed as research and development costs prior to fda approval in 2008 ; therefore , the costs of these supplies were not included in costs of goods sold . other income and expense investment income decreased to $ 4.5 million in 2009 from $ 18.2 million in 2008 , due primarily to lower yields on , and lower balances of , cash and marketable securities . in addition , in 2009 and 2008 , deterioration in the credit quality of specific marketable securities in our investment portfolio subjected us to the risk of not being able to recover these securities 2019 carrying values . as a result , in 2009 and 2008 , we recognized charges of $ 0.1 million and $ 2.5 million , respectively , related to these securities , which we considered to be other than temporarily impaired . in 2009 and 2008 , these charges were either wholly or partly offset by realized gains of $ 0.2 million and $ 1.2 million , respectively , on sales of marketable securities during the year. .