condition mean min max ZT0-3 8.400285 8.400285 8.400285 ZT4-7 7.417725 7.417725 7.417725 ZT8-11 7.04281 7.04281 7.04281 ZT12-15 7.37013 7.37013 7.37013 ZT16-19 9.30582 9.30582 9.30582 ZT20-23 9.369050000000001 9.369050000000001 9.369050000000001