Year Number of 1990 206.85 1991 213.07 1992 219.47 1993 226.12 1994 233.49 1995 241.9 1996 247.94 1997 254.48 1998 261.48 1999 269.02 2000 277.27 2001 283.14 2002 288.78 2003 294.07 2004 300.88 2005 309.08 2006 312.21 2007 315.16 2008 318.17 2009 321.55 2010 325.41 2011 333.67 2012 341.94 2013 350.45 2014 360.69 2015 372.26 2016 384.5