Year Number of 1990 2470.93 1991 2583.98 1992 2715.22 1993 2861.48 1994 3021.67 1995 3209.33 1996 3388.55 1997 3584.72 1998 3798.61 1999 4035.14 2000 4302.76 2001 4548.84 2002 4823.12 2003 5123.93 2004 5452.37 2005 5816.24 2006 6047.68 2007 6295.18 2008 6565.7 2009 6852.6 2010 7161.77 2011 7351.38 2012 7547.55 2013 7747.74 2014 7966.38 2015 8208.74 2016 8426.56