Year Number of 1990 2431.9 1991 2508.97 1992 2591.67 1993 2674.63 1994 2762.15 1995 2857.91 1996 2970.39 1997 3090.23 1998 3214.53 1999 3345.3 2000 3480.73 2001 3552.97 2002 3626.96 2003 3701.92 2004 3780.52 2005 3867.21 2006 3932.06 2007 3999.85 2008 4070.75 2009 4142.47 2010 4218.34 2011 4202.28 2012 4188.47 2013 4177.47 2014 4165.57 2015 4150.22 2016 4150.78