Year Number of 1990 213.16 1991 215.96 1992 218.39 1993 221.75 1994 225.25 1995 228.62 1996 231.12 1997 233.95 1998 236.43 1999 240.51 2000 244.25 2001 249.74 2002 255.16 2003 261.87 2004 268.72 2005 275.72 2006 282.5 2007 289.01 2008 296.73 2009 304.89 2010 312.65 2011 323.37 2012 335.36 2013 347.64 2014 360.5 2015 374.2 2016 388.27