Year Number of 1990 315.56 1991 324.46 1992 326.58 1993 332.48 1994 333.13 1995 332.37 1996 329.16 1997 308.41 1998 305.55 1999 309.67 2000 310.3 2001 315.8 2002 320.69 2003 326.5 2004 333.22 2005 344.36 2006 350.58 2007 359.18 2008 363.93 2009 368.7 2010 377.52 2011 383.81 2012 384.06 2013 391.21 2014 398.37 2015 413.86 2016 427