Year	% of cohort
1997	75.9361572265625
1998	76.260139465332
1999	76.157096862793
2000	74.9374923706055
2001	73.9650421142578
2002	73.1534576416016
2003	72.3242263793945
2004	71.6072082519531
2005	71.9609069824219
2006	61.8874092102051
2007	61.5592308044434
2008	72.7335891723633
2009	67.5619583129883
2010	63.3733901977539
2011	67.165657043457
2012	68.1797180175781
2013	75.8733978271484
2014	75.010986328125
2015	73.8593597412109
2016	71.8102798461914
2017	70.7368927001953
2018	66.8317718505859
2019	66.9897308349609