Year	billion cubic meters
1997	0.297
1998	0.3026666667
1999	0.3083333333
2000	0.314
2001	0.3202
2002	0.3264
2003	0.3326
2004	0.3388
2005	0.309
2006	0.3135333333
2007	0.3180666667
2008	0.3226
2009	0.3271333333
2010	0.3316666667
2011	0.3362
2012	0.3362
2013	0.3362
2014	0.3362
2015	0.3362
2016	0.3362
2017	0.3362
2018	0.3362
2019	0.3362
2020	0.3362