Year kg per hectare 1961 2125.9558391180867 1962 2303.369526366128 1963 2383.9652314704213 1964 2323.7986725385194 1965 2517.753562603953 1966 2556.5291113695425 1967 2640.954335593632 1968 2700.7488717569363 1969 2818.546890294642 1970 2719.6471158908294 1971 3090.1676730727772 1972 3137.400705952193 1973 3109.1505942734457 1974 2889.293405023388 1975 3055.846781802311 1976 3073.2861492909824 1977 3182.7371249128364 1978 3495.7573132589696 1979 3529.130822455539 1980 3295.868393023541 1981 3506.4455311076536 1982 3638.1857636050872 1983 3227.4867322117466 1984 3826.7396399359363 1985 3922.845966723569 1986 3912.721729484267 1987 3889.2044992096476 1988 3525.46170015345 1989 3897.430088052965 1990 4089.8836596668652 1991 4050.643744668352 1992 4206.272573836452 1993 3850.1190640658087 1994 4414.604585449789 1995 4037.4013441944053 1996 4396.246406364194 1997 4429.013195743189 1998 4602.622337656809 1999 4634.396503522343 2000 4624.61337754464 2001 4578.123912896726 2002 4536.474717133522 2003 4448.504776135117 2004 5266.975281383984 2005 4893.046201575164 2006 4833.442520511586 2007 4895.495363874754 2008 5102.728901748904 2009 5279.808806273433 2010 5216.15284616798 2011 5277.588983695506 2012 4858.834538759089 2013 5582.405138202064 2014 5851.6084683931 2015 5675.099691948412 2016 6153.820516751238 2017 6079.174277307271 2018 5881.637546953639 2019 5929.845832146199 2020 5926.2688289178595 2021 5978.123011152168 2022 5874.428630566164