Year Number of 1990 1412.56 1991 1501.51 1992 1635.38 1993 1779.24 1994 1889.44 1995 2074.68 1996 2204.94 1997 2325.61 1998 2521.15 1999 2693.79 2000 2940.5 2001 3136.95 2002 3355.96 2003 3656.67 2004 3925.02 2005 4155.16 2006 4395.97 2007 4618.9 2008 4842.68 2009 5065.36 2010 5352.53 2011 5593.72 2012 5773.46 2013 5857.42 2014 5917.8 2015 5958.97 2016 5993.54