Year Number of 1990 1390.35 1991 1466.98 1992 1579.38 1993 1707.42 1994 1795.38 1995 1936.72 1996 2040.83 1997 2143.19 1998 2298.24 1999 2427.06 2000 2601.7 2001 2735.37 2002 2882.16 2003 3077.27 2004 3224.23 2005 3362.89 2006 3493.09 2007 3624.07 2008 3780.65 2009 3920.1 2010 4087.73 2011 4202.08 2012 4264.38 2013 4255.2 2014 4262.02 2015 4282.31 2016 4287.39