condition mean min max ZT0-3 6.369162 6.369162 6.369162 ZT4-7 8.600629 8.600629 8.600629 ZT8-11 8.9310385 8.9310385 8.9310385 ZT12-15 7.687705 7.687705 7.687705 ZT16-19 8.988432 8.988432 8.988432 ZT20-23 8.573861 8.573861 8.573861