Year Number of 1990 3151.8 1991 3215.61 1992 3314.4 1993 3447.11 1994 3589.5 1995 3721.89 1996 3815.36 1997 3849.74 1998 3861.72 1999 3929.26 2000 4017.12 2001 4084.13 2002 4167.63 2003 4235.34 2004 4294.03 2005 4339.41 2006 4365.8 2007 4373.19 2008 4408.9 2009 4468.65 2010 4546.3 2011 4503.34 2012 4478.59 2013 4412.37 2014 4392.7 2015 4293.09 2016 4181.77