Year	Measure
1990	0.731
1991	0.727
1992	0.711
1993	0.7
1994	0.696
1995	0.702
1996	0.711
1997	0.724
1998	0.736
1999	0.745
2000	0.757
2001	0.77
2002	0.78
2003	0.792
2004	0.798
2005	0.807
2006	0.812
2007	0.82
2008	0.825
2009	0.824
2010	0.826
2011	0.83
2012	0.834
2013	0.841
2014	0.846
2015	0.848