condition mean min max ZT0-3 8.0 8.0 8.0 ZT4-7 6.6 6.6 6.6 ZT8-11 13.7 13.7 13.7 ZT12-15 11.600000000000001 11.600000000000001 11.600000000000001 ZT16-19 7.0 7.0 7.0 ZT20-23 29.05 29.05 29.05