Year Number of 1990 247.21 1991 256.41 1992 266.41 1993 277.29 1994 288.82 1995 301.03 1996 314.3 1997 328.21 1998 343.06 1999 358.82 2000 375.71 2001 389.17 2002 403.82 2003 419.93 2004 436.81 2005 454.47 2006 481.25 2007 509.23 2008 539.46 2009 571.61 2010 606.07 2011 643.03 2012 682.73 2013 725.58 2014 770.96 2015 818.88 2016 868.51