Year	billion cubic meters
1987	0.48
1988	0.4923384615
1989	0.5046769231
1990	0.5170153846
1991	0.5293538462
1992	0.5416923077
1993	0.5540307692
1994	0.5663692308
1995	0.5787076923
1996	0.5910461538
1997	0.6033846154
1998	0.6157230769
1999	0.6280615385
2000	0.6404
2001	0.65346
2002	0.66652
2003	0.67958
2004	0.69264
2005	0.7057
2006	0.7057
2007	0.7057
2008	0.7057
2009	0.7057
2010	0.7057
2011	0.7057
2012	0.7057
2013	0.7057
2014	0.7057
2015	0.7057
2016	0.7057
2017	0.7057
2018	0.7057
2019	0.7057
2020	0.7057