Year	% of total
1990	98.41563405462055
1991	97.68075491759703
1992	98.00092621179375
1993	96.76919100542776
1994	97.06843825793526
1995	95.75081967213114
1996	95.0204081632653
1997	94.07843745155789
1998	94.15503875968993
1999	93.76344086021506
2000	93.27506243310738
2001	93.70722750792856
2002	93.49214569307786
2003	93.68614972366439
2004	93.52900789564023
2005	93.70617696160267
2006	93.81155613919894
2007	93.6166610226888
2008	93.5403520425108
2009	94.22394320748629
2010	93.34205790937347
2011	93.91634980988593
2012	95.36366770079283
2013	93.03050545535515
2014	93.79555223322743
2015	94.63142341159087