Year Number of 1990 2678.7 1991 2796.43 1992 2919.09 1993 3045.91 1994 3182.13 1995 3332.98 1996 3454.88 1997 3589.04 1998 3733.61 1999 3887.03 2000 4051.53 2001 4148.52 2002 4249.56 2003 4355.93 2004 4466.6 2005 4588.59 2006 4724.89 2007 4860.76 2008 5000.98 2009 5143.35 2010 5296.67 2011 5479.38 2012 5671.06 2013 5856.51 2014 6053.6 2015 6265.16 2016 6489.54