Year	kg per hectare
1961	489.4
1962	485.4
1963	467.3
1964	463.8
1965	463.5
1966	468.1
1967	467.3
1968	471.8
1969	475.9
1970	491
1971	498.8
1972	494.2
1973	478.7
1974	468.5
1975	473.1
1976	408.8
1977	428.7
1978	447
1979	422.6
1980	462.6
1981	530.6
1982	532.6
1983	643.6
1984	643.8
1985	746.9
1986	920.2
1987	693.7
1988	699.1
1989	792.1
1990	627.6
1991	560.9
1992	504.7
1993	452.5
1994	410.4
1995	494.6
1996	504.5
1997	481.1
1998	419.6
1999	581.7
2000	733
2001	812.7
2002	769.8
2003	688
2004	581.1
2005	650.9
2006	493.7
2007	605.8
2008	557.5
2009	416.4
2010	575.2
2011	457.2
2012	1190
2013	964
2014	582.9
2015	593.8
2016	507.3
2017	506.6
2018	710.2
2019	522.2
2020	502.5
2021	502.6
2022	502.5