Year Number of 1990 3639.55 1991 3735.47 1992 3841.56 1993 3961.85 1994 4088.3 1995 4217.13 1996 4365.07 1997 4517.54 1998 4685.45 1999 4860.08 2000 5036.68 2001 5226.35 2002 5410.12 2003 5614.49 2004 5836.7 2005 6076.3 2006 6301.73 2007 6547.2 2008 6799.9 2009 7048.15 2010 7272.56 2011 7451.35 2012 7624.12 2013 7813.47 2014 8007.76 2015 8245.69 2016 8455.31