Year Grams per day 1961 1.83 1962 2.38 1963 1.56 1964 1.68 1965 2.86 1966 5.3 1967 7.35 1968 5.72 1969 8.56 1970 5.82 1971 6.88 1972 7.44 1973 8.49 1974 6 1975 3.72 1976 4.98 1977 4.69 1978 6.82 1979 9.6 1980 7.21 1981 9.74 1982 9.55 1983 9.24 1984 8.92 1985 10.89 1986 12.83 1987 12.52 1988 12.24 1989 9.92 1990 9.57 1991 9.36 1992 9.31 1993 8.85 1994 10.37 1995 10.35 1996 10.51 1997 10.65 1998 10.5 1999 10.77 2000 12.57 2001 17.41 2002 15.85 2003 16.19 2004 17.95 2005 13.54 2006 19.83 2007 21.36 2008 25.64 2009 27.26 2010 27.21 2011 30.87 2012 37.87 2013 34.96