Year	% of total
1990	70.9328848854446
1995	71.2949954826168
2000	70.8768228294086
2005	75.5693992553786
2010	71.7879167335294
2011	68.962968170084
2012	67.4933164154681
2013	58.5259880044303
2014	53.6800438484776
2015	54.751664917967
2016	51.1789119626484
2017	51.9725798701313