Year	% of cohort
1999	98.3124694824219
2000	98.5490417480469
2001	98.7488403320312
2002	97.6841888427734
2003	98.4122314453125
2004	98.4152908325195
2005	99.3717727661133
2006	98.2241287231445
2007	98.829719543457
2008	99.5840301513672
2009	98.780647277832
2010	99.1760101318359
2011	99.2513885498047
2012	99.2305603027344
2013	99.2887191772461
2014	99.451042175293
2015	99.5149383544922
2016	99.4843521118164
2017	99.4514999389648
2018	99.5277709960938
2019	99.5787200927734
2020	99.5009918212891