Year Number of 1990 333 1991 321.44 1992 315.36 1993 305.21 1994 304.89 1995 306.99 1996 299.25 1997 305.32 1998 296.18 1999 300.26 2000 298.48 2001 295.65 2002 298.44 2003 299.05 2004 301.2 2005 311.59 2006 317.78 2007 315.53 2008 306.09 2009 301.11 2010 296.22 2011 287.76 2012 279.87 2013 280.24 2014 290.27 2015 298.4 2016 305.27