Year kg per hectare 1961 1951.5199161552132 1962 2207.96000608397 1963 2202.5237985319964 1964 2274.638315013088 1965 2339.348305946031 1966 2325.8561888054046 1967 2707.6357233575036 1968 2739.587216782577 1969 2741.7421609802855 1970 2625.48611917454 1971 3065.707110503005 1972 3070.060559790311 1973 3184.077847922629 1974 3261.5110440348512 1975 3140.569003699869 1976 2954.9666255135835 1977 3231.991661802283 1978 3587.169990671129 1979 3458.579588889687 1980 3776.344737605824 1981 3524.540871013246 1982 3773.665451759047 1983 3687.475816362492 1984 4443.380554952921 1985 4315.500142600712 1986 4091.781606303235 1987 4240.946899603618 1988 4507.360251991828 1989 4428.853471536208 1990 4489.04884955878 1991 4815.111762317151 1992 4387.606649136991 1993 4661.688512325351 1994 4626.361418054559 1995 4555.973360722841 1996 5164.1477190809765 1997 5040.906237360513 1998 5286.672225229652 1999 5160.509679236364 2000 5347.723470982155 2001 5220.012701329058 2002 5366.3839380254485 2003 4775.888541860509 2004 5862.315598360328 2005 5228.545724896938 2006 5248.245606233427 2007 5305.876365599193 2008 5786.118306250301 2009 5699.4102652953325 2010 5510.37545346084 2011 5611.63215941462 2012 5570.365600912191 2013 5832.910986430803 2014 6105.65089448584 2015 5992.852167533527 2016 5477.980547980173 2017 5750.560867427425 2018 5531.808839735434 2019 5923.347344430085 2020 5874.804030706569 2021 5936.424687341046 2022 5578.25764056774