Year Number of 1990 239.2 1991 214.68 1992 205.63 1993 204.99 1994 213.24 1995 242.38 1996 237.25 1997 243.22 1998 251.81 1999 254.66 2000 268.44 2001 279.38 2002 300.92 2003 307.85 2004 317.85 2005 330.45 2006 337.04 2007 341.68 2008 350.86 2009 352 2010 352.28 2011 346.69 2012 339.28 2013 333.63 2014 328.15 2015 326.06 2016 325.5