Year Number of 1990 402.27 1991 416.52 1992 431.88 1993 448.5 1994 465.93 1995 484.28 1996 496.16 1997 508.39 1998 521.25 1999 534.43 2000 548.17 2001 560.76 2002 573.71 2003 587.77 2004 602.33 2005 617.67 2006 633.19 2007 649.47 2008 667.88 2009 687.13 2010 707.42 2011 728.56 2012 751 2013 774.97 2014 800.38 2015 827.31 2016 855.98