condition mean min max ZT0-3 22.1 22.1 22.1 ZT4-7 18.8 18.8 18.8 ZT8-11 29.45 29.45 29.45 ZT12-15 7.1 7.1 7.1 ZT16-19 5.300000000000001 5.300000000000001 5.300000000000001 ZT20-23 1.75 1.75 1.75