Year Grams per day 1961 27.18 1962 26 1963 15.52 1964 16.4 1965 22.26 1966 23.08 1967 20.59 1968 25.11 1969 26.55 1970 27.06 1971 25.98 1972 27.37 1973 25.53 1974 19.61 1975 18.09 1976 15.66 1977 10.91 1978 9.38 1979 4.96 1980 5.17 1981 2.36 1982 5.1 1983 3.41 1984 7.28 1985 7.05 1986 7.07 1987 20.87 1988 22.31 1989 18.24 1990 16.13 1991 17.17 1992 23.28 1993 22.4 1994 16.96 1995 22.42 1996 13.4 1997 6.07 1998 12 1999 16.19 2000 20.22 2001 19.78 2002 20.07 2003 19.03 2004 22.77 2005 26.01 2006 26.48 2007 27.73 2008 26.13 2009 30.93 2010 35.77 2011 30.38 2012 25.79 2013 40.48