Year Number of 1990 200.94 1991 211.74 1992 224.11 1993 237.85 1994 252.13 1995 266.12 1996 279 1997 291.36 1998 304.19 1999 320.16 2000 336.87 2001 353.14 2002 369.11 2003 385.75 2004 405.18 2005 425.38 2006 445.72 2007 464.78 2008 484.3 2009 502.91 2010 521.8 2011 544.25 2012 570.61 2013 599.34 2014 628.42 2015 657.41 2016 688.01