condition mean min max ZT0-3 27.700000000000003 27.700000000000003 27.700000000000003 ZT4-7 7.3 7.3 7.3 ZT8-11 6.1 6.1 6.1 ZT12-15 19.95 19.95 19.95 ZT16-19 28.2 28.2 28.2 ZT20-23 6.75 6.75 6.75