Year	% of total
1990	14.594742712768088
1991	15.331165963007784
1992	16.388596129538797
1993	18.282747985359453
1994	19.96902989359032
1995	20.19929040385561
1996	19.660163369972704
1997	19.653217467156363
1998	20.53366050959704
1999	20.095372783218668
2000	19.047069803850487
2001	18.827407120673918
2002	18.621331719706884
2003	17.912790112252896
2004	19.840565800838544
2005	19.033137061804272
2006	18.38865388591166
2007	17.153778669006133
2008	16.137692998254714
2009	17.80543636597861
2010	18.248626010674837
2011	16.843047421578444
2012	16.871687970355012
2013	18.372753303895166
2014	16.551717987912028
2015	17.416885011845554