Year	% of total
1990	100
1995	99.8261324824363
2000	99.8585586532682
2005	99.8603927328863
2010	100
2011	100
2012	99.8409389397507
2013	99.7815727447258
2014	98.0718774537363
2015	99.1089483849592
2016	97.4066532146519
2017	97.4325569187238