Year Number of 1990 4411.85 1991 4706.95 1992 4742.43 1993 4750.48 1994 4862.62 1995 5096.06 1996 5153.58 1997 5344.61 1998 5461.09 1999 5664.29 2000 5644.78 2001 5735.24 2002 5858.13 2003 6003.83 2004 6221.61 2005 6402.8 2006 6610.28 2007 6843.83 2008 6980.44 2009 7090.23 2010 7178.9 2011 7299.28 2012 7496.31 2013 7560.59 2014 7466.66 2015 7495.72 2016 7559.95