Year Number of 1990 197.16 1991 200.84 1992 204.72 1993 209.89 1994 215.59 1995 221.95 1996 226.38 1997 230.8 1998 235.38 1999 240.38 2000 246 2001 252.12 2002 258.39 2003 265.66 2004 272.5 2005 279.13 2006 286.5 2007 293.69 2008 301.52 2009 309.46 2010 318.06 2011 331.6 2012 345.74 2013 361.21 2014 378.26 2015 397.49 2016 410.39