Year Grams per day 1961 5.17 1962 5.18 1963 4.77 1964 4.52 1965 5.01 1966 6.58 1967 10.21 1968 14.09 1969 19.06 1970 20.73 1971 22.89 1972 23.21 1973 25.5 1974 22.66 1975 21.3 1976 25.47 1977 32.63 1978 41.27 1979 47.14 1980 43.12 1981 38.44 1982 42.83 1983 49.71 1984 56.26 1985 58.76 1986 66.65 1987 70.71 1988 79.44 1989 86.71 1990 88.26 1991 91.65 1992 92.04 1993 87.35 1994 84.23 1995 86.38 1996 87.63 1997 92.62 1998 80.7 1999 90.82 2000 96.29 2001 99.97 2002 103.48 2003 103.08 2004 102.65 2005 104.12 2006 103.56 2007 100.03 2008 99.93 2009 95.11 2010 104.4 2011 100.06 2012 103.25 2013 105.24