Year % of tax revenue 2005 23.293630870636857 2006 22.073977552563115 2007 21.083064721870862 2008 20.538554183981816 2009 20.850990539820312 2010 21.078498303840302 2011 21.33734050344711 2012 21.48992003958366 2013 20.7844350715958 2014 21.850452574836606 2015 20.4074681652773 2016 22.08916699112961 2017 20.775671762566496 2018 19.83012806725531 2019 19.816442815858675 2020 20.33798481022085