Year	kg per hectare
1961	1541.7
1962	1553.5
1963	1501.9
1964	1512.8
1965	1559.8
1966	1514.3
1967	1549.3
1968	1808.5
1969	1944.1
1970	2000.8
1971	2081.7
1972	2152.4
1973	2127.2
1974	2280.3
1975	2307.3
1976	2472.6
1977	2424.5
1978	2493
1979	2622.4
1980	2865.7
1981	3022.1
1982	3332.1
1983	3320.3
1984	3379.4
1985	3513.3
1986	3476.2
1987	3604.7
1988	3568.3
1989	3778.6
1990	3800.2
1991	3862.1
1992	3817.1
1993	3916.3
1994	3865.5
1995	3842.8
1996	3944.9
1997	4011.4
1998	3816.9
1999	3895.7
2000	4026.4
2001	4044.9
2002	4169.5
2003	4248.1
2004	4274.5
2005	4311.3
2006	4365.8
2007	4413.9
2008	4703
2009	4808.7
2010	4872.4
2011	4891.3
2012	5086.8
2013	5087
2014	5099.1
2015	5313.8
2016	5158.7
2017	5122.3
2018	5244
2019	5196.7
2020	5248.6
2021	5331
2022	5393.5