Year Number of 1990 1966.99 1991 2134.01 1992 2286 1993 2432.73 1994 2591.58 1995 2764.9 1996 2845.42 1997 2935.73 1998 3030.88 1999 3127.72 2000 3233.78 2001 3252.15 2002 3273.35 2003 3299.3 2004 3329.51 2005 3370.14 2006 3424.22 2007 3475.68 2008 3525.33 2009 3576.67 2010 3636.55 2011 3796.3 2012 3965.96 2013 4146.76 2014 4324.8 2015 4506.85 2016 4694.59