Year billion cubic meters 2008 13.56 2009 15.9420761799 2010 18.3191523599 2011 20.6962285398 2012 23.0733047198 2013 25.4503808997 2014 27.8274570796 2015 30.2045332596 2016 32.5816094395 2017 34.9586856195 2018 37.3357617994 2019 38.55 2020 38.55