Year Number of 1990 292.9 1991 296.38 1992 298.17 1993 298.01 1994 296.59 1995 299.71 1996 297.85 1997 301.34 1998 297.26 1999 285.67 2000 277.34 2001 275.75 2002 279.92 2003 283.27 2004 286.3 2005 291.2 2006 295.97 2007 299.47 2008 302.66 2009 307.27 2010 312.51 2011 317.96 2012 329.79 2013 339.85 2014 349.09 2015 357.23 2016 366.9