Year	Measure
1990	0.477
1991	0.486
1992	0.498
1993	0.508
1994	0.519
1995	0.531
1996	0.542
1997	0.542
1998	0.562
1999	0.569
2000	0.576
2001	0.584
2002	0.592
2003	0.601
2004	0.609
2005	0.618
2006	0.625
2007	0.633
2008	0.641
2009	0.647
2010	0.655
2011	0.662
2012	0.668
2013	0.675
2014	0.678
2015	0.683