condition mean min max ZT0-3 1.396973123 0.640981794 2.152964452 ZT4-7 5.253771534749999 4.4252066375 6.082336432 ZT8-11 6.032187604 5.1563397795 6.9080354285 ZT12-15 15.635668836 13.426703957 17.844633715 ZT16-19 18.907870447500002 18.796839445 19.01890145 ZT20-23 22.63708441 21.39449118 23.879677639999997