Year per Person 1980 1.71432 1981 1.65205 1982 3.93923 1983 3.78195 1984 4.3279 1985 4.57126 1986 5.05738 1987 5.2067 1988 5.42832 1989 5.64041 1990 5.94124 1991 6.06614 1992 6.53613 1993 8.7392 1994 9.08702 1995 9.11097 1996 11.76743 1997 12.61203 1998 13.62461 1999 16.03896 2000 18.44906 2001 19.67374 2002 20.54412 2003 20.98242 2004 22.32631 2005 22.21335 2006 23.57117 2007 23.42299 2008 23.9025 2009 23.90104 2010 23.64828 2011 22.94594 2012 20.908 2013 18.50259 2014 18.0985 2015 17.71916 2016 17.36538