Year	Measure
1990	0.83
1991	0.835
1992	0.836
1993	0.84
1994	0.865
1995	0.863
1996	0.867
1997	0.867
1998	0.869
1999	0.873
2000	0.878
2001	0.882
2002	0.881
2003	0.885
2004	0.888
2005	0.893
2006	0.899
2007	0.905
2008	0.906
2009	0.906
2010	0.911
2011	0.921
2012	0.922
2013	0.923
2014	0.923
2015	0.924