Year	% of total
1990	39.15139826422372
1991	32.83113622096673
1992	40.10045366169799
1993	41.4783191026285
1994	37.898410236525784
1995	37.80686130256331
1996	36.279390365321284
1997	38.4411050394657
1998	38.148310023310025
1999	36.14839390740461
2000	36.399001761597184
2001	36.921056269874185
2002	38.74503356624195
2003	40
2004	36.61842708401545
2005	37.38837070847391
2006	38.76281839232551
2007	39.646347138203815
2008	35.45947923653882
2009	35.072852526976774
2010	35.95201476468779
2011	36.51900722588753
2012	36.56418832004116
2013	34.10715415269783
2014	24.32558410534289
2015	32.43571573192954