Year	Measure
1990	0.62
1991	0.626
1992	0.633
1993	0.638
1994	0.643
1995	0.648
1996	0.651
1997	0.656
1998	0.662
1999	0.667
2000	0.673
2001	0.683
2002	0.687
2003	0.696
2004	0.704
2005	0.713
2006	0.72
2007	0.728
2008	0.734
2009	0.74
2010	0.748
2011	0.756
2012	0.765
2013	0.769
2014	0.779
2015	0.781