Year Number of 1990 276.42 1991 288.42 1992 298.85 1993 332.39 1994 354.57 1995 363.7 1996 377.84 1997 387.7 1998 411.98 1999 423.12 2000 444.4 2001 450.44 2002 455.44 2003 463.1 2004 490.94 2005 507.09 2006 526.13 2007 540 2008 541.7 2009 549.52 2010 566.6 2011 588.5 2012 607.04 2013 636.53 2014 655.94 2015 674.44 2016 694.42