Year	kg per hectare
1961	575
1962	571.4
1963	523
1964	509.8
1965	525.3
1966	1060.2
1967	1059.7
1968	1085.7
1969	1108.8
1970	1233.8
1971	1234.6
1972	1235.3
1973	1236.3
1974	1233.8
1975	1199
1976	1225
1977	1242.7
1978	1257.7
1979	1238.8
1980	1233.5
1981	1281
1982	1352.4
1983	1230.3
1984	1286.7
1985	1252.5
1986	1235.5
1987	1262.3
1988	1276.6
1989	1166.1
1990	1028.6
1991	909.1
1992	916.7
1993	1083.3
1994	1111.1
1995	1124
1996	1249.3
1997	1245.6
1998	1293.4
1999	1277.2
2000	1278
2001	1115.4
2002	916.7
2003	833.3
2004	916.7
2005	1290
2006	1261.5
2007	1448.8
2008	1553.4
2009	1183.5
2010	1178.6
2011	1173.1
2012	1285.3
2013	1250.1
2014	1172
2015	1129.1
2016	1073.2
2017	1059.5
2018	1083.6
2019	1128.2
2020	1148.1
2021	1051.9
2022	1120.6