condition mean min max ZT0-3 8.690373 8.690373 8.690373 ZT4-7 9.049965 9.049965 9.049965 ZT8-11 8.3589005 8.3589005 8.3589005 ZT12-15 8.2235835 8.2235835 8.2235835 ZT16-19 7.903264 7.903264 7.903264 ZT20-23 8.903488500000002 8.903488500000002 8.903488500000002