Year Number of 1990 437.21 1991 436.27 1992 435.53 1993 434.28 1994 432.84 1995 431.71 1996 440.23 1997 448.79 1998 457.96 1999 468.73 2000 481.86 2001 510.74 2002 543.4 2003 580 2004 620.6 2005 665.79 2006 701.96 2007 740.01 2008 783.41 2009 830.89 2010 883.77 2011 921.47 2012 962.68 2013 1008.89 2014 1056.65 2015 1105.77 2016 1158.55