Year Number of 1990 427.62 1991 438.53 1992 456.22 1993 474.08 1994 496.32 1995 514.11 1996 527.15 1997 545.24 1998 566.92 1999 575.49 2000 580.64 2001 577.82 2002 578.8 2003 597.99 2004 609.85 2005 625.51 2006 647.43 2007 671.82 2008 696.61 2009 724.63 2010 748.36 2011 777.74 2012 807.35 2013 849.23 2014 885.67 2015 923.9 2016 957.01