Year	Measure
1990	0.495
1991	0.495
1992	0.498
1993	0.503
1994	0.515
1995	0.524
1996	0.535
1997	0.543
1998	0.552
1999	0.562
2000	0.57
2001	0.577
2002	0.583
2003	0.587
2004	0.592
2005	0.597
2006	0.601
2007	0.607
2008	0.613
2009	0.614
2010	0.62
2011	0.625
2012	0.63
2013	0.636
2014	0.642
2015	0.645