Year	% of total
1990	99.6968906582897
1995	99.7564116385534
2000	99.7168335535248
2005	99.8770854967477
2010	99.8760372413248
2011	99.8381953006909
2012	99.8561801263407
2013	99.3528605884275
2014	97.4810442275854
2015	96.3381509958462
2016	92.7433952370884
2017	92.1046289822956