Year	years
2003	2.7785714285714285
2004	2.6625
2005	2.7157894736842105
2006	2.6894736842105265
2007	2.6894736842105265
2008	2.6894736842105265
2009	2.6894736842105265
2010	2.6894736842105265
2011	2.6736842105263157
2012	2.6736842105263157
2013	2.6052631578947363
2014	2.5842105263157893
2015	2.5578947368421048
2016	2.5315789473684207
2017	2.5315789473684207
2018	2.5315789473684207
2019	2.5315789473684207