Year Number of 1990 31436.14 1991 31498.52 1992 31649.68 1993 31732.79 1994 31703.33 1995 31816.4 1996 31825.25 1997 31575.31 1998 31346.05 1999 31162.38 2000 30906.76 2001 30532.41 2002 30434.03 2003 30426.29 2004 30361.95 2005 30492 2006 30531.11 2007 30609.26 2008 30749.47 2009 30942.12 2010 31033.94 2011 31031.48 2012 31162.14 2013 31327.37 2014 31156.82 2015 31366.19 2016 31692.64