Year Number of 1990 313.87 1991 335.94 1992 347.64 1993 385.37 1994 404.11 1995 405.84 1996 399.03 1997 391.27 1998 405.07 1999 405.96 2000 412.3 2001 440.87 2002 446.78 2003 455.45 2004 462.95 2005 492.03 2006 501.27 2007 520.92 2008 504.08 2009 478.65 2010 487.44 2011 482.25 2012 483.43 2013 489.08 2014 475.03 2015 472.89 2016 472.23