Year kg per hectare 1961 1917.6220707743275 1962 2062.7683318066133 1963 2079.5687660156204 1964 2161.4267287308926 1965 2281.0997794147165 1966 2300.8737992877927 1967 2563.8507486624244 1968 2594.081202026019 1969 2619.113211027089 1970 2505.6444763896366 1971 2938.1641553565714 1972 3010.5252104715055 1973 3078.5382876986214 1974 3187.2530581573255 1975 3051.274071406703 1976 3028.979371425075 1977 3170.4070355023646 1978 3459.5974015468146 1979 3300.8845479087327 1980 3542.78270267382 1981 3383.1596324301695 1982 3693.377364729953 1983 3526.190709680518 1984 4187.011886879604 1985 3979.7591165460553 1986 3904.974167128234 1987 3943.5768890033355 1988 4139.480262788988 1989 4183.562409533352 1990 4187.193354098447 1991 4408.242171473436 1992 3751.188995097226 1993 3980.887024428681 1994 3995.1933035540965 1995 4112.5471294008175 1996 4379.944833254876 1997 4476.6925355074945 1998 4531.439859158709 1999 4521.7106115811 2000 4397.748545977639 2001 4556.3652804861595 2002 4605.361716476027 2003 4144.74489610358 2004 5238.2895088796095 2005 4711.529796718368 2006 4562.01292024807 2007 4491.058111371341 2008 5105.972953000448 2009 4969.022729383238 2010 4916.014727529474 2011 5061.007648404112 2012 4821.251304868363 2013 5253.38897627744 2014 5612.193014551919 2015 5377.756274907766 2016 5193.830592104411 2017 5499.551101945192 2018 5230.171922938209 2019 5574.786763385186 2020 5465.240411423273 2021 5663.963137191217 2022 5260.315093567103