Year	Measure
1990	0.781
1991	0.786
1992	0.791
1993	0.799
1994	0.804
1995	0.808
1996	0.811
1997	0.815
1998	0.816
1999	0.819
2000	0.825
2001	0.833
2002	0.841
2003	0.851
2004	0.861
2005	0.87
2006	0.881
2007	0.887
2008	0.892
2009	0.894
2010	0.898
2011	0.905
2012	0.907
2013	0.913
2014	0.916
2015	0.917