Year	% (cumulative)
1972	2.99389004707336
1981	8.18871021270752
1993	18.4397106170654
2004	11.7591495513916
2005	15.1386804580688
2006	16.0016593933105
2007	17.0619201660156
2008	17.227710723877
2009	17.832389831543
2010	19.9095706939697
2011	20.9165000915527
2012	21.7303199768066
2013	20.5774402618408
2014	20.9666900634766
2015	20.8408794403076
2018	21.1450805664062