Year	kg per hectare
1961	1487.8
1962	1516
1963	1399.4
1964	1539.2
1965	1551.1
1966	1574.9
1967	1669.1
1968	1522.3
1969	1629.1
1970	1750.7
1971	1750.2
1972	1698.3
1973	1711.9
1974	1743.1
1975	1842.5
1976	1924.7
1977	1952.6
1978	1796.2
1979	1883.4
1980	1818.2
1981	2135
1982	2170
1983	2087.3
1984	2522.8
1985	2328.1
1986	2300
1987	2552.8
1988	2480.8
1989	2523.8
1990	2603.1
1991	2296
1992	2500.2
1993	2696.2
1994	2907.9
1995	2641.4
1996	2858.3
1997	2765.5
1998	2750.4
1999	3109.9
2000	3084.1
2001	3241.3
2002	3372.9
2003	3442.5
2004	3278
2005	3557.9
2006	3520.5
2007	3485.6
2008	3833.2
2009	3919
2010	3897.9
2011	3898
2012	4149.6
2013	4101.3
2014	4017
2015	4242.2
2016	4370.1
2017	4216.5
2018	4530.8
2019	4369.6
2020	4557.2
2021	4704.1
2022	4634.6