As an Air Traffic Controller, I've often been asked about the frequency of bird strikes and the outcomes of the encounters. The following link has some data on this situation but shows only the most serious occurrences from January 2000 through December 2008. The report mentions that there were over 82,000 incidents reported during this time period from the US and over 200 foreign airports. As amazing as this number is, it is estimated that this accounts for only about 20% of the strikes that have actually occurred. 
You'll need Adobe Acrobat Reader to open the file:
http://wildlife.pr.erau.edu/sig_strikes_2008.pdf
 Edward Boyd
Westminster, MD