condition mean min max ZT0-3 0.536262 0.536262 0.536262 ZT4-7 0.5054339999999999 0.5054339999999999 0.5054339999999999 ZT8-11 0.2906865 0.2906865 0.2906865 ZT12-15 0.3215565 0.3215565 0.3215565 ZT16-19 0.41360299999999994 0.41360299999999994 0.41360299999999994 ZT20-23 0.379328 0.379328 0.379328