Year	Measure
1990	0.86
1991	0.861
1992	0.866
1993	0.871
1994	0.874
1995	0.877
1996	0.878
1997	0.881
1998	0.884
1999	0.885
2000	0.884
2001	0.887
2002	0.889
2003	0.892
2004	0.895
2005	0.898
2006	0.901
2007	0.905
2008	0.907
2009	0.907
2010	0.91
2011	0.913
2012	0.915
2013	0.916
2014	0.918
2015	0.92