Year Number of 1990 796.74 1991 785.59 1992 782.22 1993 766.51 1994 753.04 1995 746.88 1996 740.32 1997 735.99 1998 720.76 1999 703.86 2000 685.11 2001 677.85 2002 668.93 2003 667 2004 666.29 2005 656.34 2006 643.51 2007 639.45 2008 632.91 2009 617.41 2010 598.38 2011 572.81 2012 541.61 2013 474.48 2014 526.2 2015 544.49 2016 559.89