Year	kg per hectare
1961	1758.3
1962	1788.6
1963	1842.8
1964	1990.2
1965	2057.7
1966	2196.3
1967	1970.1
1968	1948.9
1969	2162.6
1970	2378.5
1971	2653.8
1972	2892.6
1973	3025.1
1974	3208.7
1975	2377.4
1976	2603
1977	2568
1978	2780.1
1979	2922.5
1980	3005.1
1981	3145.4
1982	3753.9
1983	3966
1984	3463.7
1985	3617.2
1986	3754.8
1987	3705.8
1988	3499.2
1989	3726.2
1990	3996.2
1991	3979.6
1992	6090.2
1993	4015.2
1994	3636.7
1995	3856.3
1996	3835.6
1997	3950.7
1998	3635.3
1999	3983.1
2000	4159.3
2001	4304.8
2002	4343.4
2003	4000.8
2004	3824.8
2005	3808.6
2006	4262.9
2007	4368.1
2008	4468.8
2009	3954.3
2010	4436
2011	4605.6
2012	3747.7
2013	4031.5
2014	4965.6
2015	5109.8
2016	5172.1
2017	5174.7
2018	5040.8
2019	5087.2
2020	5130
2021	5232
2022	5223.6