condition mean min max ZT0-3 6.5 6.5 6.5 ZT4-7 3.9 3.9 3.9 ZT8-11 9.6 9.6 9.6 ZT12-15 7.449999999999999 7.449999999999999 7.449999999999999 ZT16-19 3.3 3.3 3.3 ZT20-23 5.75 5.75 5.75