condition mean min max ZT0-3 9.084432 9.084432 9.084432 ZT4-7 9.2172315 9.2172315 9.2172315 ZT8-11 8.753557 8.753557 8.753557 ZT12-15 8.936426 8.936426 8.936426 ZT16-19 8.7840205 8.7840205 8.7840205 ZT20-23 8.931637 8.931637 8.931637