Year	kg per hectare
1961	1440.8
1962	1440
1963	1438.8
1964	1439.4
1965	1437.5
1966	1437.7
1967	1435.1
1968	1432.7
1969	1435.2
1970	1436.7
1971	1437
1972	1441
1973	1439.7
1974	1442.6
1975	1447.9
1976	1438.9
1977	1444.4
1978	1443.3
1979	1434.2
1980	1425
1981	1457.7
1982	1445.3
1983	1429
1984	1442.3
1985	1386.1
1986	1371.9
1987	1181.9
1988	1019.7
1989	1015.2
1990	1279.8
1991	1027.5
1992	1063.6
1993	1164.2
1994	1281.1
1995	1365.8
1996	1467.5
1997	1541
1998	1559.5
1999	1506.7
2000	1437.9
2001	1449.4
2002	1549
2003	1791.3
2004	2995.2
2005	2334.9
2006	2199.7
2007	1999.2
2008	2741.5
2009	2160.4
2010	2469.1
2011	2801.7
2012	2944.2
2013	3226.4
2014	3254.9
2015	3475.8
2016	3373.4
2017	3411.5
2018	3416.5
2019	3083.5
2020	3435.2
2021	3344
2022	3448.9