Year Number of 1990 2839.39 1991 2967.59 1992 3106.12 1993 3240.61 1994 3353.26 1995 3498.86 1996 3596.89 1997 3678.8 1998 3711.92 1999 3632.28 2000 3580.39 2001 3505.78 2002 3505.21 2003 3452.83 2004 3432.82 2005 3387.05 2006 3359.03 2007 3374.81 2008 3310.11 2009 3320.32 2010 3315.8 2011 3329.23 2012 3376.33 2013 3468.85 2014 3560.91 2015 3708.04 2016 3843.6