Year Number of 1990 331.91 1991 343.73 1992 356.09 1993 368.83 1994 382.05 1995 397.01 1996 407.65 1997 418.38 1998 429.98 1999 441.28 2000 454.42 2001 470.6 2002 485.88 2003 501.71 2004 518.38 2005 536.03 2006 555.34 2007 575.07 2008 596.19 2009 618.39 2010 642.08 2011 652.28 2012 661.07 2013 671.13 2014 681.27 2015 691.48 2016 702.18