swimmer   wk1  wk3  wk5  wk7  wk9 wk11
swimmer1 23.1 23.2 22.9 22.9 22.8 22.7
swimmer2 23.2 23.1 23.4 23.5 23.5 23.4
swimmer3 22.7 22.6 22.8 22.8 22.9 22.8
swimmer4 23.7 23.6 23.7 23.5 23.5 23.4