Year Number of 1990 467.62 1991 480.43 1992 506.31 1993 508.36 1994 533.81 1995 538.79 1996 577.08 1997 633.4 1998 659.31 1999 687.7 2000 723.06 2001 730.71 2002 746.82 2003 763.65 2004 776.11 2005 789.4 2006 810.2 2007 815.97 2008 815.68 2009 823.55 2010 837.65 2011 831.44 2012 818.27 2013 816.6 2014 828.85 2015 839.71 2016 845.57