Year	% of total
1990	98.8103869010938
1995	98.7706835386595
2000	98.5314339931347
2005	98.4156007629672
2010	98.1121664773954
2011	98.5776220506368
2012	97.8486487255829
2013	97.2633861745502
2014	96.583070041503
2015	96.7545739375126
2016	94.5484844180311
2017	94.7772139982593