condition mean min max ZT0-3 5.904061666666667 3.9736450000000003 7.296810000000001 ZT4-7 2.7239050000000002 2.7239050000000002 2.7239050000000002 ZT8-11 2.85281 2.85281 2.85281 ZT12-15 4.167855 4.138695 4.197015 ZT16-19 4.5093 4.5093 4.5093 ZT20-23 7.92812 7.92812 7.92812