Year Number of 1990 294 1991 301.48 1992 306.49 1993 321.79 1994 328.87 1995 334.41 1996 336.53 1997 336.89 1998 347 1999 364.02 2000 371.88 2001 388.58 2002 403.61 2003 415.27 2004 427.91 2005 437.33 2006 445.56 2007 453.76 2008 462.67 2009 472.6 2010 483.21 2011 498.97 2012 516.05 2013 534.29 2014 553.87 2015 575.09 2016 594.77