Year	% of total
1990	13.944698930364202
1991	14.906594821576203
1992	15.635952980305087
1993	17.325845544945697
1994	18.82388613696941
1995	19.157747448467006
1996	18.6601897491656
1997	18.69290378968433
1998	19.60221476654562
1999	19.289034609954818
2000	18.09773249992125
2001	17.938383500877205
2002	17.75183969503667
2003	16.86187448483287
2004	18.855657199722227
2005	18.29073742297454
2006	17.548515381331615
2007	16.301482780524044
2008	15.52641672141716
2009	17.069977442945515
2010	17.736219396499557
2011	15.999291409338253
2012	15.929368685028802
2013	17.55638976281907
2014	16.11991393531339
2015	16.61795003833097