Year Number of 1990 5867.32 1991 6155.87 1992 6415.26 1993 6517.84 1994 6643.42 1995 6792.31 1996 6988.8 1997 7241.66 1998 7400.1 1999 8106.11 2000 8839.63 2001 9322.3 2002 9697.37 2003 10138.43 2004 10329.29 2005 10610.5 2006 10912.14 2007 11180.76 2008 11369.76 2009 11546.95 2010 11709.44 2011 11944.35 2012 12274.2 2013 12661.59 2014 12992.61 2015 13467.22 2016 13981.32