Year	kg per hectare
1961	415.8
1962	419.3
1963	420.7
1964	398.2
1965	383.6
1966	366.8
1967	353.4
1968	358.4
1969	352.7
1970	354.1
1971	343.5
1972	346.7
1973	347.4
1974	350.9
1975	355.1
1976	354.3
1977	361.6
1978	366.1
1979	371
1980	376.8
1981	383.3
1982	385.1
1983	399
1984	414.3
1985	321.7
1986	401.6
1987	355.4
1988	395.1
1989	441.6
1990	457.1
1991	547
1992	159
1993	356.1
1994	334.5
1995	220.1
1996	274
1997	446.6
1998	379
1999	214.4
2000	391.2
2001	440.9
2002	270.8
2003	301.5
2004	418.3
2005	465.6
2006	620.5
2007	481.3
2008	495.5
2009	364.8
2010	405
2011	427.5
2012	431.1
2013	458.7
2014	226.1
2015	370.7
2016	261.5
2017	426.3
2018	502.5
2019	965.1
2020	549.3
2021	494
2022	649