Year Number of 1990 13399.96 1991 13815.69 1992 14235.62 1993 14703.4 1994 15071.97 1995 15410.57 1996 15601.98 1997 15794.73 1998 16106.54 1999 16336.65 2000 16384.22 2001 16596.91 2002 16809.89 2003 17117.27 2004 17254.77 2005 17482.31 2006 17549.59 2007 17734.88 2008 17773.2 2009 17796.63 2010 17746.03 2011 17680.62 2012 17676.57 2013 17329.31 2014 17033.58 2015 16883.68 2016 16788.29