condition mean min max ZT0-3 7.811539 7.811539 7.811539 ZT4-7 8.387276499999999 8.387276499999999 8.387276499999999 ZT8-11 7.881449999999999 7.881449999999999 7.881449999999999 ZT12-15 8.7590305 8.7590305 8.7590305 ZT16-19 9.396964 9.396964 9.396964 ZT20-23 9.015930999999998 9.015930999999998 9.015930999999998