Year Grams per day 1961 18.97 1962 21.11 1963 18.88 1964 19.34 1965 19.41 1966 20.35 1967 20.31 1968 21.19 1969 21.66 1970 24.76 1971 27.83 1972 30.25 1973 29.11 1974 23.34 1975 17.91 1976 19.08 1977 19.18 1978 22.74 1979 18.23 1980 19.05 1981 17.4 1982 17.48 1983 16.95 1984 17.58 1985 17.45 1986 16.93 1987 13.59 1988 12.79 1989 12.9 1990 12.26 1991 16.98 1992 17.83 1993 16.77 1994 15.43 1995 17.06 1996 22.34 1997 20.12 1998 18.81 1999 22.04 2000 22.04 2001 21.81 2002 21.47 2003 24.45 2004 24.11 2005 26.69 2006 26.26 2007 27.19 2008 26.25 2009 26.84 2010 28.56 2011 29.33 2012 29.81 2013 27.96