condition mean min max ZT0-3 17.699325 16.5467 18.851950000000002 ZT4-7 20.215400000000002 20.215400000000002 20.215400000000002 ZT8-11 23.3226 23.3226 23.3226 ZT12-15 0 0 0 ZT16-19 24.598 24.598 24.598 ZT20-23 19.9553 19.9553 19.9553