Year	% of total
1990	98.37883138809053
1995	98.39381597880205
2000	98.32724134877206
2005	98.56502375285545
2010	98.26467757778643
2011	98.48248391586647
2012	98.386757935899
2013	97.72577576993682
2014	97.56742991846949
2015	97.82479001217433
2016	96.85376017953094
2017	96.88651332274759