Year Number of 1990 407.7 1991 420.56 1992 441.72 1993 462.81 1994 490.09 1995 512.25 1996 527.35 1997 548.36 1998 573.39 1999 579.86 2000 580.44 2001 568.6 2002 561.91 2003 576.07 2004 581.9 2005 592.71 2006 612.53 2007 636.71 2008 662.97 2009 692.46 2010 715.81 2011 744.26 2012 776.03 2013 822.17 2014 862.91 2015 903.74 2016 944.37