_id año valor 1 2006 32.5 2 2007 29.6 3 2008 24.2 4 2009 21 5 2010 18.5 6 2011 13.7 7 2012 12.4 8 2013 11.5 9 2014 9.7 10 2015 9.7 11 2016 9.4 12 2017 7.9 13 2018 8.1 14 2019 8.8