Year	kg per hectare
1961	1265.6
1962	1380
1963	1291
1964	1627.5
1965	1652.6
1966	1823.8
1967	1950.1
1968	1521.6
1969	1717
1970	2113.1
1971	2142.5
1972	2189.9
1973	2201.9
1974	2440.2
1975	2424.5
1976	2608.1
1977	2061.6
1978	2798.1
1979	2635.8
1980	3321.9
1981	3312.5
1982	3455
1983	2929.5
1984	3596.1
1985	3015.6
1986	3602.8
1987	3714.5
1988	3862.7
1989	4022
1990	3035.8
1991	4124
1992	3606.8
1993	3553.2
1994	3886.8
1995	3751
1996	3710.3
1997	3799
1998	3581.1
1999	3648.8
2000	3868.8
2001	3847.6
2002	3747.2
2003	3693.6
2004	4017.4
2005	4049.8
2006	3918.9
2007	3929.9
2008	4515.8
2009	4266.2
2010	4064.9
2011	4344.1
2012	4206.7
2013	4393.3
2014	4286.5
2015	4214.9
2016	4223.5
2017	4317.2
2018	3799.6
2019	4043.5
2020	4197.1
2021	4194.7
2022	4142.6