condition mean min max ZT0-3 6.199999999999999 6.199999999999999 6.199999999999999 ZT4-7 7.7 7.7 7.7 ZT8-11 8.4 8.4 8.4 ZT12-15 11.45 11.45 11.45 ZT16-19 7.8 7.8 7.8 ZT20-23 8.25 8.25 8.25