Year Number of 1990 2196.56 1991 2250.95 1992 2306.41 1993 2367.27 1994 2432.46 1995 2503.72 1996 2607.14 1997 2715.43 1998 2836.87 1999 2964.7 2000 3102.61 2001 3228.61 2002 3363.79 2003 3516.04 2004 3673.3 2005 3836.73 2006 3989.61 2007 4148.67 2008 4320.48 2009 4502.36 2010 4695.87 2011 4911.31 2012 5134.81 2013 5365.11 2014 5606.07 2015 5859.45 2016 6123.15