Year	Measure
1990	0.818
1991	0.82
1992	0.825
1993	0.836
1994	0.845
1995	0.851
1996	0.855
1997	0.86
1998	0.863
1999	0.864
2000	0.868
2001	0.873
2002	0.881
2003	0.884
2004	0.886
2005	0.888
2006	0.891
2007	0.894
2008	0.895
2009	0.899
2010	0.901
2011	0.904
2012	0.908
2013	0.91
2014	0.913
2015	0.915