Year Number of 1990 197.67 1991 200.75 1992 204.03 1993 207.75 1994 211.73 1995 216.61 1996 219.58 1997 224.41 1998 227.03 1999 230.43 2000 236.06 2001 237.83 2002 244.1 2003 249.96 2004 256.68 2005 262.89 2006 268.75 2007 273.3 2008 300.9 2009 280.52 2010 284.57 2011 284.47 2012 297.93 2013 310.79 2014 323.87 2015 337.32 2016 350.8