Cohort progression — Uks "Kraszak"
Median season-best times of each birth-year cohort, overlaid by age — shows how consecutive groups developed at the same stage of training.
Event: 50 breaststroke50 freestyle100 breaststroke100 freestyle200 breaststroke50 backstroke50 butterfly100 medley100 backstroke200 freestyle
50 m breaststroke men · 25 m pool
X: swimmer age in season · Y: median season-best time
born 2013 born 2010 born 2009