condition mean min max ZT0-3 20.60485 19.9488 21.2609 ZT4-7 13.6232 13.6232 13.6232 ZT8-11 14.503250000000001 14.503250000000001 14.503250000000001 ZT12-15 0 0 0 ZT16-19 22.60115 22.60115 22.60115 ZT20-23 22.6976 22.6976 22.6976