Year	% of cohort
1999	95.6066436767578
2000	95.8686218261719
2001	94.0486831665039
2002	93.8632736206055
2003	94.2741012573242
2004	93.6596832275391
2005	94.4029388427734
2006	93.385856628418
2007	86.4870300292969
2008	91.4133224487305
2009	93.1188812255859
2013	95.9405975341797