condition mean min max ZT0-3 7.449999999999999 7.449999999999999 7.449999999999999 ZT4-7 1.2 1.2 1.2 ZT8-11 6.1 6.1 6.1 ZT12-15 3.0 3.0 3.0 ZT16-19 8.15 8.15 8.15 ZT20-23 14.75 14.75 14.75