Year	% of total
1990	35.1917311957306
1995	30.1293075465254
2000	44.5477086949321
2005	48.2422384039837
2010	43.5193337492411
2011	50.781467321187
2012	36.5451306312633
2013	24.9176458300973
2014	19.0344314937296
2015	23.1426584508701
2016	13.0241310881886
2017	13.4018384258943