condition mean min max ZT0-3 6.846455 6.846455 6.846455 ZT4-7 4.0832250000000005 4.0832250000000005 4.0832250000000005 ZT8-11 8.224645 8.224645 8.224645 ZT12-15 7.168215 7.168215 7.168215 ZT16-19 13.5766 13.5766 13.5766 ZT20-23 8.777165 8.777165 8.777165