condition mean min max ZT0-3 8.123048 8.123048 8.123048 ZT4-7 8.172502999999999 8.172502999999999 8.172502999999999 ZT8-11 7.9724805 7.9724805 7.9724805 ZT12-15 7.5987655 7.5987655 7.5987655 ZT16-19 7.628849 7.628849 7.628849 ZT20-23 8.1545565 8.1545565 8.1545565