Year	Measure
1990	0.378
1991	0.382
1992	0.391
1993	0.403
1994	0.415
1995	0.422
1996	0.429
1997	0.429
1998	0.436
1999	0.443
2000	0.444
2001	0.446
2002	0.447
2003	0.451
2004	0.461
2005	0.466
2006	0.475
2007	0.475
2008	0.476
2009	0.484
2010	0.487
2011	0.491
2012	0.501
2013	0.509
2014	0.513
2015	0.513