condition mean min max ZT0-3 1.95 1.95 1.95 ZT4-7 1.7 1.7 1.7 ZT8-11 2.65 2.65 2.65 ZT12-15 2.7 2.7 2.7 ZT16-19 1.9500000000000002 1.9500000000000002 1.9500000000000002 ZT20-23 6.55 6.55 6.55