Year	years
2003	3.6363636363636362
2004	3.609090909090909
2005	3.609090909090909
2006	3.536363636363636
2007	3.1727272727272724
2008	3.1727272727272724
2009	3.1545454545454548
2010	2.872727272727273
2011	2.7454545454545456
2012	2.7454545454545456
2013	2.6545454545454543
2014	2.690909090909091
2015	2.581818181818182
2016	2.581818181818182
2017	2.581818181818182
2018	2.581818181818182
2019	2.581818181818182