condition mean min max ZT0-3 8.948263 8.948263 8.948263 ZT4-7 8.269606 8.269606 8.269606 ZT8-11 8.071282 8.071282 8.071282 ZT12-15 7.492293 7.492293 7.492293 ZT16-19 7.330436499999999 7.330436499999999 7.330436499999999 ZT20-23 8.347967 8.347967 8.347967