Year	% of total
1990	91.57005687865507
1991	91.62634908820245
1992	91.69780292862238
1993	90.14901089819742
1994	86.17558022199799
1995	87.50243770720512
1996	87.58257393543141
1997	87.50192307692308
1998	87.5043239393631
1999	87.0899827361152
2000	85.27784272465124
2001	85.75021545280265
2002	84.73141133317336
2003	86.46228039958663
2004	87.94383449100008
2005	88.16896841422613
2006	83.51312502616632
2007	83.3912112587796
2008	90.19009797452911
2009	91.25142929742091
2010	90.2935411272173
2011	90.89575681980921
2012	91.76874925929516
2013	92.4946161457424
2014	92.12224464156546
2015	91.12597212307924