Year Number of 1990 516.03 1991 671.08 1992 875.64 1993 1144.87 1994 1500.8 1995 1972.72 1996 2287.39 1997 2654.25 1998 3082.22 1999 3582.63 2000 4169.65 2001 3832.02 2002 3523.06 2003 3240.47 2004 2982.6 2005 2749.81 2006 3049.11 2007 3384.3 2008 3768.58 2009 4198.11 2010 4677.35 2011 4799.38 2012 4926.24 2013 5054.2 2014 5186.53 2015 5325.38 2016 5471.24