condition mean min max ZT0-3 2.4723716666666666 2.237055 2.667205 ZT4-7 2.6449949999999998 2.6449949999999998 2.6449949999999998 ZT8-11 2.492445 2.492445 2.492445 ZT12-15 3.3254725 2.982055 3.66889 ZT16-19 2.373665 2.373665 2.373665 ZT20-23 3.1742049999999997 3.1742049999999997 3.1742049999999997