Year per Person 1985 0.68587 1986 0.63304 1987 0.56607 1988 0.51401 1989 0.48783 1990 0.44472 1991 0.38616 1992 0.33265 1993 0.30473 1994 0.28982 1995 0.29121 1996 0.29629 1997 0.30303 1998 0.29418 1999 0.29929 2000 0.29824 2001 0.30794 2002 0.31914 2003 0.33209 2004 0.35018 2005 0.35607 2006 0.36168 2007 0.36347 2008 0.37033 2009 0.37718 2010 0.3639 2011 0.36993 2012 0.36819 2013 0.38452 2014 0.36474 2015 0.36112 2016 0.36005