condition mean min max ZT0-3 4.9 4.9 4.9 ZT4-7 3.8 3.8 3.8 ZT8-11 5.800000000000001 5.800000000000001 5.800000000000001 ZT12-15 7.9 7.9 7.9 ZT16-19 8.55 8.55 8.55 ZT20-23 19.4 19.4 19.4