Year	Grams per day
1961	6.03
1962	11.52
1963	7
1964	7.8
1965	5.65
1966	13.06
1967	13.74
1968	17.52
1969	12.47
1970	10.96
1971	6.58
1972	9.73
1973	8.94
1974	4.14
1975	2.9
1976	3.31
1977	17.03
1978	11.03
1979	20.01
1980	19.55
1981	14.41
1982	29.76
1983	19.46
1984	26.31
1985	27.78
1986	29.85
1987	15.53
1988	17.02
1989	16.46
1990	12.12
1991	11.56
1992	10.2
1993	5.47
1994	4.42
1995	7.57
1996	11.81
1997	9.01
1998	11.02
1999	11.16
2000	7.76
2001	7.85
2002	12.85
2003	15.03
2004	16.07
2005	15.49
2006	18.01
2007	21.59
2008	23.82
2009	27.86
2010	30.47
2011	33.09
2012	33.68
2013	33.25