Year Number of 1990 355.31 1991 361.35 1992 369.08 1993 376.58 1994 384.2 1995 391.77 1996 397.13 1997 398.84 1998 402.23 1999 407.74 2000 414.67 2001 420.65 2002 427.19 2003 436.2 2004 445.84 2005 457.13 2006 472.25 2007 488.88 2008 507.79 2009 527.73 2010 552.05 2011 581.05 2012 613.26 2013 649.62 2014 688.36 2015 730.79 2016 773.67