Year Number of 1990 12943.01 1991 13366.53 1992 14700.55 1993 17114.49 1994 18330.98 1995 17607.02 1996 16552.06 1997 15704.3 1998 15527.5 1999 16300.12 2000 17012.37 2001 17205.95 2002 17668.1 2003 17900.25 2004 17877 2005 18228.59 2006 17648.84 2007 17728.55 2008 18148.66 2009 17737.48 2010 17946.68 2011 17773.02 2012 17548.35 2013 17730.63 2014 18043.44 2015 18512.03 2016 18924.59