Year	kg per hectare
1961	845.2
1962	941.8
1963	982.3
1964	1023.3
1965	1037.3
1966	1318.6
1967	1464.1
1968	1553.7
1969	1639.8
1970	1646.1
1971	1753.6
1972	1768.7
1973	1843
1974	1934.5
1975	2028.9
1976	2445.1
1977	2550.1
1978	2620.2
1979	2634.8
1980	2364
1981	2500.6
1982	2715.2
1983	3046
1984	2966.3
1985	2900.6
1986	2990.3
1987	2965.6
1988	2875
1989	2961.7
1990	2794.4
1991	2071.9
1992	2158.6
1993	2685
1994	2460.9
1995	2841.5
1996	2450.9
1997	2833.3
1998	2872.1
1999	2798.1
2000	3175.1
2001	3030.8
2002	3291.9
2003	3185.7
2004	3466.3
2005	3462.1
2006	3602.6
2007	3728.4
2008	4081.2
2009	4315.3
2010	4761.8
2011	4750.7
2012	4883.8
2013	4949.8
2014	4892.6
2015	4873.8
2016	4716.4
2017	4813
2018	4840.5
2019	5038.2
2020	5209.2
2021	5144.7
2022	5200.7