condition mean min max ZT0-3 18.1 18.1 18.1 ZT4-7 9.4 9.4 9.4 ZT8-11 32.35 32.35 32.35 ZT12-15 2.75 2.75 2.75 ZT16-19 37.650000000000006 37.650000000000006 37.650000000000006 ZT20-23 40.9 40.9 40.9