Year	Measure
1990	0.652
1991	0.641
1992	0.621
1993	0.619
1994	0.596
1995	0.594
1996	0.591
1997	0.593
1998	0.593
1999	0.595
2000	0.597
2001	0.607
2002	0.617
2003	0.63
2004	0.64
2005	0.648
2006	0.656
2007	0.661
2008	0.668
2009	0.664
2010	0.672
2011	0.679
2012	0.686
2013	0.696
2014	0.701
2015	0.699