Year	% (cumulative)
1972	2.99389
1981	8.18871
1993	18.43971
2004	11.75915
2005	15.13868
2006	16.00166
2007	17.06192
2008	17.22771
2009	17.83239
2010	19.90957
2011	20.9165
2012	21.73032
2013	20.57744
2014	20.88549
2015	20.84088
2018	21.14508