Year	% of total
1990	38.1061918028515
1995	37.7927683651228
2000	36.2152769663941
2005	37.2764507811338
2010	35.7249265164177
2011	35.4725728325688
2012	22.3799809900012
2013	26.6263858231337
2014	16.2530796327983
2015	17.6644609863411
2016	8.53102443315827
2017	9.7305722145438