Year Number of 1990 7006.55 1991 6958.62 1992 6935.83 1993 6977.71 1994 6971.98 1995 6993.03 1996 6943.36 1997 6885.13 1998 6919.66 1999 7018.39 2000 7017.96 2001 6996.28 2002 6998.45 2003 6956.51 2004 6862.64 2005 6794.29 2006 6724.67 2007 6672.58 2008 6652.18 2009 6601.99 2010 6624.35 2011 6655.5 2012 6709.54 2013 6793.87 2014 6892.12 2015 7038.79 2016 7177.28