Year	Measure
1990	0.745
1991	0.751
1992	0.757
1993	0.765
1994	0.768
1995	0.775
1996	0.778
1997	0.779
1998	0.783
1999	0.786
2000	0.794
2001	0.796
2002	0.798
2003	0.803
2004	0.806
2005	0.81
2006	0.813
2007	0.815
2008	0.814
2009	0.81
2010	0.812
2011	0.812
2012	0.815
2013	0.82
2014	0.823
2015	0.824