Year	kilograms per hectare of arable land
1961	0.65
1962	0.6435643564356436
1963	1.0392156862745099
1964	1.3398058252427185
1965	1.6346153846153846
1966	2.2857142857142856
1967	2.492830188679245
1968	3.2166355140186917
1969	2.6572222222222224
1970	3.7509259259259258
1971	2.7339449541284404
1972	2.2497247706422017
1973	2.9688073394495413
1974	3.0825454545454547
1975	2.2522522522522523
1976	2.330178571428571
1977	6.000705965407695
1978	6.313176095052314
1979	5.528653780942692
1980	5.418612521150592
1981	5.916412859560068
1982	5.724873096446701
1983	7.219796954314721
1984	8.162944162436549
1985	8.307952622673435
1986	7.655986509274873
1987	8.397976391231028
1988	6.174242424242424
1989	4.814814814814815
1990	3.67003367003367
1991	3.042016806722689
1992	3.5067114093959733
1993	3.742281879194631
1994	5.033557046979865
1995	5.033557046979865
1996	5.704697986577181
1997	6.575503355704698
1998	6.633053691275168
1999	8.307046979865772
2000	7.732214765100671
2001	8.809060402684564
2002	9.768624161073825
2003	8.15520134228188
2004	11.062751677852349
2005	7.9989937950695955
2006	9.032198557772933
2007	8.622840851920174
2008	6.557437531443904
2009	7.002850913969478
2010	9.239032258064515
2011	11.035967741935483
2012	10.335733870967742
2013	10.05833870967742
2014	9.621035483870967
2015	13.59095806451613
2016	10.903622580645159
2017	13.02838064516129
2018	13.385329032258067
2019	13.385329032258067
2020	13.385329032258067
2021	13.385329032258067