condition mean min max ZT0-3 7.376876 7.376876 7.376876 ZT4-7 7.2069795 7.2069795 7.2069795 ZT8-11 7.235 7.235 7.235 ZT12-15 7.1683425 7.1683425 7.1683425 ZT16-19 7.7372795 7.7372795 7.7372795 ZT20-23 8.193678 8.193678 8.193678