Year Number of 1990 181.82 1991 184.61 1992 187.6 1993 190.28 1994 192.56 1995 194.58 1996 203.44 1997 212.37 1998 222.02 1999 233.02 2000 245.94 2001 273.88 2002 306.71 2003 345.21 2004 389.53 2005 440.44 2006 467.89 2007 497.05 2008 531.38 2009 569.12 2010 611.17 2011 625.83 2012 642.31 2013 662.81 2014 684.81 2015 708.34 2016 732.78