Year Number of 1990 2639.82 1991 2901.47 1992 3179.46 1993 3483.6 1994 3822.14 1995 4204.92 1996 4586 1997 5021.64 1998 5519.19 1999 6062.4 2000 6649.37 2001 7251.88 2002 7898 2003 8621.74 2004 9413.95 2005 10283.07 2006 10935.93 2007 11639.46 2008 12437.58 2009 13313.46 2010 14264.5 2011 14964.86 2012 15703.73 2013 16517.64 2014 17352.44 2015 18208.18 2016 19108.84