Year	Measure
1990	0.634
1991	0.644
1992	0.65
1993	0.653
1994	0.654
1995	0.658
1996	0.66
1997	0.664
1998	0.667
1999	0.67
2000	0.672
2001	0.684
2002	0.688
2003	0.687
2004	0.7
2005	0.714
2006	0.728
2007	0.745
2008	0.754
2009	0.754
2010	0.756
2011	0.767
2012	0.77
2013	0.771
2014	0.769
2015	0.767