Year Number of 1990 415.57 1991 429.55 1992 442.64 1993 450.49 1994 457.49 1995 464.47 1996 479.04 1997 484.47 1998 492.46 1999 502.2 2000 501.78 2001 511.36 2002 520.45 2003 531.09 2004 543.09 2005 555.83 2006 574.68 2007 586.55 2008 595.19 2009 608.28 2010 621.85 2011 627.63 2012 640.62 2013 645.2 2014 652.4 2015 648.15 2016 652.02