Year Number of 1990 205.94 1991 212.35 1992 219.37 1993 226.6 1994 234.43 1995 243.1 1996 250.43 1997 258.53 1998 267.74 1999 277.9 2000 289.3 2001 300.05 2002 312 2003 325.06 2004 339.33 2005 355.34 2006 366 2007 377.24 2008 389.49 2009 402.15 2010 415.89 2011 432.45 2012 449.58 2013 468.44 2014 487.75 2015 507.56 2016 528.62