Year kg per hectare 1961 2177.90583580428 1962 2386.40248030469 1963 2465.3921690769566 1964 2402.395493282467 1965 2594.0442916605934 1966 2638.205859157611 1967 2720.0704273966803 1968 2777.778226327288 1969 2915.6194591134863 1970 2824.0017322596727 1971 3185.683279708786 1972 3223.319870284661 1973 3185.9778132890156 1974 2933.181234592225 1975 3133.427950142065 1976 3122.9847986513378 1977 3248.7077903886448 1978 3582.342910729192 1979 3644.883465311132 1980 3373.863646565425 1981 3605.5712578873477 1982 3721.4912652695452 1983 3273.713346286947 1984 3908.389849409369 1985 4004.45370467905 1986 3995.6946340092345 1987 3977.090138996118 1988 3566.061012459156 1989 3974.170484032772 1990 4176.999976217155 1991 4133.773760032939 1992 4241.467464715048 1993 3888.1209043702684 1994 4405.558022526866 1995 3963.541828085256 1996 4325.398660343425 1997 4349.884642829638 1998 4520.744597630456 1999 4530.393881866557 2000 4580.301764714091 2001 4506.511088665084 2002 4479.857335234684 2003 4383.361549185427 2004 5155.610688452065 2005 4795.496679916628 2006 4756.670905089267 2007 4811.702492406504 2008 5082.160892224868 2009 5207.5847152821825 2010 5086.68624170532 2011 5222.494417325731 2012 4808.969545536487 2013 5535.47471433062 2014 5820.256818930879 2015 5665.240927037883 2016 6155.176994615496 2017 5999.182174725755 2018 5883.045218695774 2019 5936.135678093401 2020 5865.511890606766 2021 5985.688586305659 2022 5871.2422837932845