Year	% of total
1990	35.63074890001412
1991	35.69950780801201
1992	35.610339165028385
1993	35.47761541632439
1994	35.17602771817996
1995	34.765519407263994
1996	34.993661022449025
1997	34.35060501572389
1998	34.36481983748596
1999	34.405289419908755
2000	34.86075347557236
2001	34.51586312144035
2002	35.57325432000491
2003	35.002137870639324
2004	35.29111061587916
2005	35.47512734136023
2006	35.65616351814095
2007	35.259946143437745
2008	35.83541782686698
2009	33.97912984599427
2010	33.71056389193773
2011	33.32531564571157
2012	30.957639415085822
2013	30.4969866773747
2014	30.460812514784614
2015	27.49480407147232
2016	25.528322291962244