Year	% (cumulative)
1970	18.7000007629395
1975	23.8999996185303
1980	34.4931907653809
1985	42.4743003845215
2005	43.5780487060547
2006	44.8062782287598
2007	46.2761688232422
2008	48.8844184875488
2012	56.0329704284668
2013	50.8304901123047
2015	55.8721008300781
2017	56.0804710388184
2018	55.9323883056641