condition mean min max ZT0-3 22.900000000000002 22.900000000000002 22.900000000000002 ZT4-7 7.6 7.6 7.6 ZT8-11 5.05 5.05 5.05 ZT12-15 2.7 2.7 2.7 ZT16-19 8.5 8.5 8.5 ZT20-23 5.5 5.5 5.5