Year Grams per day 1961 30.95 1962 33.76 1963 36.48 1964 35.8 1965 38.3 1966 36.29 1967 36.19 1968 36.36 1969 36.23 1970 36.07 1971 35.88 1972 36.84 1973 35.8 1974 36.25 1975 53.27 1976 59.02 1977 59.3 1978 63.44 1979 53.66 1980 56.09 1981 56.9 1982 60.76 1983 53 1984 51.83 1985 39.48 1986 42.93 1987 44.98 1988 44.42 1989 45.79 1990 46.85 1991 45.98 1992 46.89 1993 45.98 1994 45.12 1995 44.38 1996 42.84 1997 42.67 1998 42.42 1999 42.97 2000 42.98 2001 43.35 2002 44.74 2003 47.62 2004 46.63 2005 45.59 2006 46.76 2007 47.21 2008 46.79 2009 47.18 2010 46.87 2011 46.39 2012 48.96 2013 45.47