condition mean min max ZT0-3 27.222425 22.5824 31.862450000000003 ZT4-7 30.7408 30.7408 30.7408 ZT8-11 33.21125 33.21125 33.21125 ZT12-15 0 0 0 ZT16-19 31.4968 31.4968 31.4968 ZT20-23 31.43515 31.43515 31.43515