Year	cubic meters
1961	23.95639935317722
1962	23.073506423087352
1963	22.23568716611726
1964	21.43772074153076
1965	20.724100055955073
1966	20.09858355232415
1967	19.52019364032091
1968	18.97524205293144
1969	18.45903939159006
1970	17.973085304756125
1971	17.31661702569786
1972	16.451224176719048
1973	15.586520776832195
1974	14.780491229626016
1975	14.029377516519592
1976	13.331378064550533
1977	12.684841931013487
1978	12.087805821487283
1979	11.53745201141054
1980	11.031591720790413
1981	10.59799168057653
1982	10.229734257078336
1983	9.882106469815106
1984	9.541597788257633
1985	9.20863309352518
1986	8.8850189695155
1987	8.573296325270862
1988	8.275799287039892
1989	7.99441989491335
1990	7.730693559172661
1991	7.470840376156813
1992	7.214096344256678
1993	6.971616805082309
1994	6.7424745555866465
1995	6.525988116175641
1996	6.321552067463604
1997	6.128925001876984
1998	5.9480969063948
1999	5.779236071679866
2000	5.622383834521999
2001	5.47752366632569
2002	5.345278248459223
2003	5.139696963467034
2004	4.799322335686201
2005	4.434978229800614
2006	4.119545078636966
2007	3.844187396447202
2008	3.6024904016146366
2009	3.391402624776062
2010	3.2958566961508513
2011	3.3001203718905647
2012	3.265468729463263
2013	3.170393596439014
2014	3.0507941979995943
2015	2.9365514021298806
2016	2.837561654894333
2017	2.74568001570529
2018	2.6893649064773357
2019	2.6770393016139873
2020	2.7073326073169723