Year kg per hectare 1961 1421.619314413351 1962 1510.8631936906513 1963 1576.0941040595567 1964 1576.946325117763 1965 1625.014969154917 1966 1665.7642100833218 1967 1748.6653014239166 1968 1765.7077356630248 1969 1789.4100389355801 1970 1816.3886234858633 1971 1965.6043414343994 1972 1953.469567402063 1973 1985.4378856929409 1974 1966.8677468754645 1975 2080.3896368213886 1976 2088.6776925136164 1977 2135.9346717779576 1978 2296.3669451594333 1979 2331.575509925803 1980 2297.408449743149 1981 2438.7213567994813 1982 2534.2880040777804 1983 2443.6247664327198 1984 2691.7911832656205 1985 2695.3594708180376 1986 2690.086521294144 1987 2677.4875226392355 1988 2600.408101858725 1989 2754.9956663382936 1990 2870.9491318841324 1991 2859.4172697199065 1992 2775.591612336837 1993 2735.201253704066 1994 2818.809958751589 1995 2758.0860917515447 1996 2938.759949652844 1997 2987.7859704943803 1998 3060.0874164657916 1999 3099.407411871992 2000 3069.1889245938632 2001 3126.78362014272 2002 3101.7667102697274 2003 3094.621704496169 2004 3373.077844103067 2005 3262.695741296 2006 3307.428616462562 2007 3373.1392426117777 2008 3537.64309891583 2009 3555.4766270911655 2010 3546.90743044674 2011 3656.0464809851874 2012 3614.7924624156794 2013 3822.7962752171384 2014 3896.249288002097 2015 3928.000854852105 2016 4008.427394185337 2017 4075.0440669067693 2018 4035.038574778137 2019 4131.819598130346 2020 4100.768039365954 2021 4152.2327183892685 2022 4182.3829704231275