condition mean min max ZT0-3 31.7 31.7 31.7 ZT4-7 17.0 17.0 17.0 ZT8-11 19.75 19.75 19.75 ZT12-15 21.25 21.25 21.25 ZT16-19 60.650000000000006 60.650000000000006 60.650000000000006 ZT20-23 14.2 14.2 14.2