Year Number of 1990 207.57 1991 215.08 1992 209.42 1993 221.45 1994 223.51 1995 226.06 1996 216.08 1997 205.88 1998 206.56 1999 205 2000 204.62 2001 215.12 2002 212.13 2003 224.31 2004 223.29 2005 233.87 2006 238.06 2007 239.39 2008 241.76 2009 223.21 2010 221.03 2011 226.89 2012 229.62 2013 231.93 2014 226.63 2015 229.31 2016 229.5