Year Number of 1990 197.84 1991 205.66 1992 216.7 1993 226.47 1994 237.36 1995 249.82 1996 253.85 1997 262.44 1998 268.14 1999 266.52 2000 267.11 2001 270.55 2002 270.62 2003 272.1 2004 276.69 2005 282.82 2006 291.59 2007 297.19 2008 303.98 2009 310.53 2010 317.33 2011 328.02 2012 339.4 2013 352.95 2014 366.65 2015 381.1 2016 394.42