Year	Measure
1990	0.547
1991	0.551
1992	0.557
1993	0.563
1994	0.57
1995	0.577
1996	0.585
1997	0.592
1998	0.593
1999	0.606
2000	0.612
2001	0.617
2002	0.621
2003	0.623
2004	0.629
2005	0.636
2006	0.644
2007	0.651
2008	0.659
2009	0.665
2010	0.671
2011	0.673
2012	0.681
2013	0.686
2014	0.688
2015	0.691