condition mean min max ZT0-3 3.5322566666666666 2.070755 4.332775 ZT4-7 1.9899650000000002 1.9899650000000002 1.9899650000000002 ZT8-11 2.7004900000000003 2.7004900000000003 2.7004900000000003 ZT12-15 4.30044 3.94969 4.65119 ZT16-19 4.23166 4.23166 4.23166 ZT20-23 5.887765 5.887765 5.887765