Year Number of 1990 328.62 1991 337.67 1992 347.01 1993 357.07 1994 367.82 1995 379.56 1996 391.52 1997 404.22 1998 417.89 1999 432.72 2000 448.62 2001 461.01 2002 474.48 2003 488.69 2004 503.96 2005 520.48 2006 535.54 2007 551.55 2008 569 2009 587.28 2010 604.96 2011 623.93 2012 645.27 2013 667.77 2014 691.37 2015 714.6 2016 738.66