Year	kg per hectare
1961	1360.4
1962	1373.3
1963	1566.5
1964	1462.1
1965	1694.2
1966	1438.5
1967	1490.5
1968	1230.2
1969	1345.5
1970	1374.8
1971	1755.9
1972	1983.8
1973	2018.4
1974	1758.7
1975	2009.2
1976	2470.9
1977	3139.7
1978	2795.3
1979	2809.5
1980	3196.2
1981	3751.8
1982	4125.3
1983	3940.7
1984	3563.6
1985	3625.9
1986	3656.8
1987	3574.1
1988	3303.6
1989	3629.6
1990	3743.1
1991	3136.4
1992	3026
1993	2703.7
1994	2607.1
1995	2508.5
1996	3500
1997	3904.8
1998	3790.7
1999	3869.7
2000	4007.5
2001	4000
2002	4781.3
2003	4013.6
2004	4083.2
2005	4129
2006	4032.3
2007	4238.8
2008	4714.3
2009	4789.2
2010	4691.1
2011	4670.9
2012	4639.7
2013	4668.6
2014	4740.4
2015	4824.3
2016	4820.4
2017	4879.9