Year Number of 1990 9718.35 1991 10100.81 1992 10509.98 1993 10924.82 1994 11347.65 1995 11793.51 1996 12102.59 1997 12431.62 1998 12774.66 1999 13122.14 2000 13477.78 2001 13722.14 2002 13970.08 2003 14217.7 2004 14481.04 2005 14760.37 2006 14854.65 2007 14960.48 2008 15070.64 2009 15187.49 2010 15312.46 2011 15400.68 2012 15479.33 2013 15582.76 2014 15686.77 2015 15791.34 2016 15899.54