Actually for Masters it fluctuates. The economy has probably taken its toll the last two years. From Don Ramseys site and the AMA site:
These are actual participants not total registered which is higher.

1995 - 40
1996 - 36
1997 - 36
1998 - 32
1999 - 38
2000 - 44
2001 - 37
2002 - 50
2003 - 37
2004 - 39
2005 - 38
2006 - 40
2007 - 37
2008 - 45
2009 - 32
2010 - 33