condition mean min max ZT0-3 6.6 6.6 6.6 ZT4-7 41.1 41.1 41.1 ZT8-11 5.300000000000001 5.300000000000001 5.300000000000001 ZT12-15 4.6 4.6 4.6 ZT16-19 4.199999999999999 4.199999999999999 4.199999999999999 ZT20-23 3.8 3.8 3.8