condition mean min max ZT0-3 8.396465 7.66723 9.1257 ZT4-7 9.182 9.182 9.182 ZT8-11 6.4478 6.4478 6.4478 ZT12-15 0 0 0 ZT16-19 9.085885000000001 9.085885000000001 9.085885000000001 ZT20-23 9.448995 9.448995 9.448995