condition mean min max ZT0-3 19.244625 18.1343 20.35495 ZT4-7 22.40045 22.40045 22.40045 ZT8-11 20.2228 20.2228 20.2228 ZT12-15 0 0 0 ZT16-19 20.175150000000002 20.175150000000002 20.175150000000002 ZT20-23 19.696550000000002 19.696550000000002 19.696550000000002