Year	% of total
1990	67.474539209978
1995	67.7757356953351
2000	68.8857497527017
2005	65.0592842103407
2010	65.1259082009935
2011	69.3939107014424
2012	72.8234196438572
2013	67.8280604082883
2014	72.5283986635133
2015	55.5785958433137
2016	56.0016460673167
2017	55.2897570936648