Year Number of 1990 10785.54 1991 11175.96 1992 11579.1 1993 12012.82 1994 12400.9 1995 12810.43 1996 13233.04 1997 13729.4 1998 14267.96 1999 14836.58 2000 15374.2 2001 15817.43 2002 16203.92 2003 16595.55 2004 16974.34 2005 17382.95 2006 17697.35 2007 18081.71 2008 18401.15 2009 18877.76 2010 19340.44 2011 19828.94 2012 20393.74 2013 21012.05 2014 21684.46 2015 22422.62 2016 23210.31