Year Number of 1990 5332.24 1991 5454.56 1992 5578.52 1993 5630.59 1994 5682.25 1995 5741.08 1996 5625.98 1997 5525.95 1998 5411.17 1999 5276.1 2000 5136.75 2001 5103.18 2002 5064.42 2003 5024.98 2004 4970.24 2005 4934.43 2006 4986.65 2007 5052.89 2008 5112.55 2009 5178.01 2010 5259.58 2011 5383.92 2012 5519.07 2013 5654.88 2014 5797.91 2015 6002.04 2016 6230.09