condition mean min max ZT0-3 20.884886 20.884886 20.884886 ZT4-7 19.776211000000004 19.776211000000004 19.776211000000004 ZT8-11 17.2152375 17.2152375 17.2152375 ZT12-15 19.804988 19.804988 19.804988 ZT16-19 18.2685125 18.2685125 18.2685125 ZT20-23 17.2819815 17.2819815 17.2819815