Year	% of cohort
1997	92.7738723754883
1998	98.2698593139648
2001	97.4138336181641
2002	98.0590591430664
2003	98.3814163208008
2004	97.8721923828125
2005	98.3794784545898
2009	98.6543731689453
2010	96.8801116943359
2011	98.9682922363281
2012	99.2456817626953
2013	98.516487121582
2014	99.907829284668
2015	97.9326324462891
2016	98.1383972167969
2019	98.1703262329102