Year	% of total
1990	22.062961679329256
1991	22.830262966658577
1992	23.721373212403908
1993	23.764763084868296
1994	22.80753420118366
1995	22.36828784995017
1996	24.079482168734398
1997	25.44027937054932
1998	23.56652151445612
1999	24.3978263908456
2000	25.726921248352532
2001	24.655256683594313
2002	23.005153633962774
2003	21.816512182134268
2004	21.450285114185363
2005	19.27737570126165
2006	17.80576120251891
2007	16.784608658382435
2008	16.980707729023433
2009	16.0251705443438
2010	16.51752533150617
2011	15.537351666377004
2012	15.749467678393728
2013	15.89839529426308
2014	16.124772432445663
2015	16.726638628159197
2016	16.90352807177465