Year	% (cumulative)
1970	18.8999996185303
1975	26.6000003814697
1980	37.2793998718262
1985	50.0874481201172
1988	41.7326889038086
2005	52.5363502502441
2006	55.1656188964844
2007	55.3842506408691
2008	59.694149017334
2012	64.0228881835938
2013	61.7840690612793
2015	64.4744110107422
2017	65.319221496582
2018	65.7795333862305