condition mean min max ZT0-3 12.7 12.7 12.7 ZT4-7 6.6 6.6 6.6 ZT8-11 6.050000000000001 6.050000000000001 6.050000000000001 ZT12-15 8.9 8.9 8.9 ZT16-19 8.65 8.65 8.65 ZT20-23 8.35 8.35 8.35