Year	% (cumulative)
1970	2.5
1975	4.09999990463257
1980	7.42387008666992
1985	11.6172304153442
1988	15.8018102645874
2005	18.0938892364502
2006	18.155969619751
2007	17.4361305236816
2008	18.1244106292725
2012	20.375
2013	17.6259593963623
2015	20.2772407531738
2017	24.2572803497314
2018	25.5614490509033