condition mean min max ZT0-3 8.317018 8.317018 8.317018 ZT4-7 9.550727 9.550727 9.550727 ZT8-11 8.6985265 8.6985265 8.6985265 ZT12-15 7.5327765 7.5327765 7.5327765 ZT16-19 8.535683 8.535683 8.535683 ZT20-23 8.539682500000001 8.539682500000001 8.539682500000001