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 arcalyst ae 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. .