condition mean min max ZT0-3 8.732799 8.732799 8.732799 ZT4-7 8.259766500000001 8.259766500000001 8.259766500000001 ZT8-11 8.9838065 8.9838065 8.9838065 ZT12-15 9.779165500000001 9.779165500000001 9.779165500000001 ZT16-19 8.6832305 8.6832305 8.6832305 ZT20-23 9.197719 9.197719 9.197719