Year	Measure
1990	0.866
1991	0.867
1992	0.871
1993	0.874
1994	0.876
1995	0.885
1996	0.888
1997	0.891
1998	0.894
1999	0.897
2000	0.899
2001	0.902
2002	0.905
2003	0.908
2004	0.91
2005	0.915
2006	0.918
2007	0.921
2008	0.925
2009	0.927
2010	0.927
2011	0.93
2012	0.933
2013	0.936
2014	0.937
2015	0.939