condition mean min max ZT0-3 7.91411 7.91411 7.91411 ZT4-7 8.201796666666667 8.201796666666667 8.201796666666667 ZT8-11 8.21232 8.21232 8.21232 ZT12-15 7.65306 7.65306 7.65306 ZT16-19 8.067459999999999 8.067459999999999 8.067459999999999 ZT20-23 8.025500000000001 8.025500000000001 8.025500000000001