Year Number of 1990 419.49 1991 428.34 1992 438.61 1993 449.74 1994 461.11 1995 473.02 1996 480.12 1997 487.56 1998 495.22 1999 503.11 2000 511.79 2001 527.75 2002 544.5 2003 563.52 2004 582.84 2005 603.16 2006 619.67 2007 636.51 2008 656.32 2009 677.28 2010 699.93 2011 721.7 2012 745.61 2013 768.31 2014 792.38 2015 817.86 2016 846.44