Year	Measure
1990	0.76
1991	0.77
1992	0.771
1993	0.769
1994	0.772
1995	0.774
1996	0.777
1997	0.782
1998	0.792
1999	0.794
2000	0.801
2001	0.811
2002	0.823
2003	0.83
2004	0.839
2005	0.85
2006	0.855
2007	0.853
2008	0.857
2009	0.859
2010	0.86
2011	0.858
2012	0.86
2013	0.862
2014	0.865
2015	0.866