Year	kg per hectare
1961	1051.2
1962	1077.6
1963	1102.4
1964	1129.2
1965	1156.9
1966	1211.6
1967	1209.4
1968	1209.3
1969	1209.1
1970	1209.2
1971	1209.5
1972	1210
1973	1140.2
1974	1215.3
1975	1093.4
1976	1000.7
1977	924.8
1978	952.2
1979	1000.2
1980	1131.7
1981	1377
1982	1282.3
1983	1442.3
1984	1343.8
1985	1433
1986	1363
1987	1563.2
1988	1289.4
1989	1424.6
1990	1468.5
1991	1316.9
1992	1328.5
1993	1328.6
1994	1310.8
1995	1540.4
1996	1579
1997	1570
1998	1089.9
1999	1170.2
2000	1368.1
2001	1447.1
2002	1341.8
2003	1533.4
2004	1388.1
2005	1506.5
2006	1522.3
2007	1682.7
2008	1680.5
2009	1727.2
2010	1660.3
2011	1711.5
2012	1646.9
2013	1667.9
2014	1854.7
2015	1821.3
2016	1890.9
2017	1865.7
2018	1847
2019	1856.1
2020	1866.6
2021	1870.7
2022	1875.6