Year Number of 1990 14618.16 1991 15143.81 1992 15667.03 1993 16183.97 1994 16592.97 1995 16952.4 1996 17105.85 1997 17259.87 1998 17514.61 1999 17807.36 2000 17984.76 2001 18291.6 2002 18607.14 2003 19026.41 2004 19328 2005 19713.82 2006 19977.96 2007 20370.81 2008 20638.8 2009 20834.19 2010 20940.85 2011 20981.57 2012 21046.51 2013 20780.91 2014 20555.14 2015 20500.79 2016 20542.68