Year Number of 1990 5358.71 1991 5566.32 1992 5734.27 1993 5869.54 1994 5905.28 1995 5927.29 1996 5997.73 1997 5998.25 1998 5979.79 1999 5951.77 2000 5950.58 2001 5943.18 2002 5934.04 2003 6003.19 2004 6050.82 2005 6037.32 2006 6064.11 2007 6096.79 2008 6075.96 2009 6027.1 2010 5932.15 2011 5786.68 2012 5670.83 2013 5523.23 2014 5457.95 2015 5395.53 2016 5341.61