condition mean min max ZT0-3 5.800000000000001 5.800000000000001 5.800000000000001 ZT4-7 21.3 21.3 21.3 ZT8-11 8.4 8.4 8.4 ZT12-15 4.4 4.4 4.4 ZT16-19 6.6 6.6 6.6 ZT20-23 3.9 3.9 3.9