condition mean min max ZT0-3 3.4233566666666664 1.97592 5.967205 ZT4-7 4.03603 4.03603 4.03603 ZT8-11 2.12803 2.12803 2.12803 ZT12-15 4.8069725000000005 4.480745000000001 5.1332 ZT16-19 2.50645 2.50645 2.50645 ZT20-23 2.379455 2.379455 2.379455