Year Number of 1990 166.38 1991 176.4 1992 186.91 1993 198.46 1994 210.86 1995 224.32 1996 246.73 1997 271.74 1998 300.46 1999 332.04 2000 366.79 2001 396.56 2002 428.88 2003 465.41 2004 504.86 2005 547.66 2006 572.63 2007 598.81 2008 627.66 2009 657.93 2010 689.81 2011 711.61 2012 734.41 2013 758.28 2014 783.89 2015 811.49 2016 838.9