Year Number of 1990 2428.65 1991 2581.48 1992 2746.43 1993 2925.59 1994 3127.81 1995 3355.78 1996 3531.56 1997 3713.34 1998 3904.81 1999 4119.65 2000 4358.07 2001 4504.22 2002 4652.01 2003 4797.98 2004 4959.8 2005 5132.14 2006 5314.83 2007 5490.09 2008 5663.28 2009 5845.89 2010 6037.7 2011 6263.86 2012 6501.4 2013 6746.03 2014 7019 2015 7307.33 2016 7614.68