condition mean min max ZT0-3 12.600000000000001 12.600000000000001 12.600000000000001 ZT4-7 6.9 6.9 6.9 ZT8-11 13.45 13.45 13.45 ZT12-15 5.8 5.8 5.8 ZT16-19 21.0 21.0 21.0 ZT20-23 13.15 13.15 13.15