Year	% of total
1990	10.457890339784157
1991	10.118161518422033
1992	10.562145560513175
1993	10.020143587624606
1994	8.057592963537509
1995	8.18169544411275
1996	8.128662895084522
1997	8.180769230769231
1998	8.17987587750534
1999	8.669838730051792
2000	10.677265996414933
2001	10.677665019258843
2002	10.67841349285249
2003	10.678608336203926
2004	10.67891552767197
2005	10.690229486933836
2006	11.168483190755962
2007	6.590250398182721
2008	10.215743149874887
2009	16.334646169482912
2010	8.889722430607652
2011	9.170073683967384
2012	16.1834577717444
2013	16.717109985837066
2014	19.199946701183997
2015	18.39332005860916