Year Number of 1990 341.71 1991 345.11 1992 354.45 1993 375.22 1994 393.81 1995 413.51 1996 415.36 1997 406.78 1998 397.09 1999 393.35 2000 397.2 2001 398.43 2002 400.9 2003 400.77 2004 404.34 2005 403.59 2006 409.69 2007 413.41 2008 422.76 2009 428.09 2010 430.38 2011 432.25 2012 432.91 2013 434.73 2014 436.29 2015 438.52 2016 441.32