Year	years
2003	3.0564102564102558
2004	3.0564102564102558
2005	3.0488888888888885
2006	3.0377777777777775
2007	3.0260869565217403
2008	3.0260869565217403
2009	3.026086956521739
2010	3.0260869565217394
2011	2.9891304347826093
2012	2.9787234042553186
2013	2.8711538461538457
2014	2.8711538461538457
2015	2.8942307692307696
2016	2.8942307692307687
2017	2.9038461538461533
2018	2.9038461538461533
2019	2.836538461538461