condition mean min max ZT0-3 7.024475 6.453685 7.5952649999999995 ZT4-7 9.64964 9.64964 9.64964 ZT8-11 6.299135 6.299135 6.299135 ZT12-15 0 0 0 ZT16-19 7.11977 7.11977 7.11977 ZT20-23 6.894425 6.894425 6.894425