Year Number 1996 19.1256828308105 1998 15.8469944000244 2000 14.7540979385376 2002 10.2702703475952 2003 16.2162170410156 2004 15.4228858947754 2005 25.4901962280273 2006 18.536584854126 2007 20.8737869262695 2008 20.3883495330811 2009 20.5741634368896 2010 19.6172256469727 2011 21.3270149230957 2012 21.3270149230957 2013 21.3270149230957 2014 17.3076915740967 2015 14.7619047164917 2016 21.4285717010498 2017 20 2018 31.9047622680664 2019 32.3809509277344 2020 32.8571434020996 2021 28.0952377319336 2022 29.7169818878174