condition mean min max ZT0-3 0.7451751666666667 0.546745 0.9880975000000001 ZT4-7 2.695095 2.695095 2.695095 ZT8-11 2.11493 2.11493 2.11493 ZT12-15 5.0429200000000005 4.244915000000001 5.840925 ZT16-19 2.81533 2.81533 2.81533 ZT20-23 1.6637 1.6637 1.6637