Year Number of 1990 242.93 1991 249.54 1992 254.6 1993 255.51 1994 258.15 1995 263.98 1996 278.65 1997 296.79 1998 320.22 1999 346.01 2000 373.79 2001 401.65 2002 432.82 2003 473.03 2004 513.87 2005 554.99 2006 583.39 2007 609.16 2008 637.49 2009 667.62 2010 701.33 2011 726.16 2012 754.68 2013 783.9 2014 814.02 2015 844.6 2016 879.45