Here is the progress that we've made so far!

  2002 2003 2004 2005 2006 2007 2008 2009
  F M F M F M F M F M F M F M F M
January     10 12 6 8 7 9 1 1     2     1
February               1     1       2  
March             1 1       3 1   1  
April                 3 1 2 3        
May             1 1 4 6 2 1        
June     2   1 1       4   1   1 2  
July       2   1   1 3 4   1 2 1 1 4
August 2 1     3   7 5   4 1 3     2  
September     6 1 2       4 4   1 1   1 3
October   1       1     2 2 1 1     1 2
November 2               2 5       1   2
December       2 1   4 4           1    

Females =  97
Males   = 113
Total   =  210

Each year, these females, left unspayed, could potentially produce 2-3 litters of 3-5 kittens each.  By spaying them, we've prevented 576-1440 kittens from being born!  This doesn't even take into account the males, which have the ability to father innumerable numbers of kittens each year.