condition mean min max ZT0-3 7.699999999999999 7.699999999999999 7.699999999999999 ZT4-7 3.0 3.0 3.0 ZT8-11 8.95 8.95 8.95 ZT12-15 9.35 9.35 9.35 ZT16-19 5.25 5.25 5.25 ZT20-23 17.2 17.2 17.2