Year Number of 1990 93.98 1991 96.79 1992 100.02 1993 103.78 1994 108.04 1995 111.86 1996 116.01 1997 120.27 1998 125.9 1999 127.48 2000 132.01 2001 136.23 2002 138.82 2003 147.72 2004 149.88 2005 155.26 2006 161.06 2007 168.32 2008 179 2009 184.31 2010 191.89 2011 196.91 2012 202.81 2013 209.91 2014 217.34 2015 224.5 2016 232.09