condition mean min max ZT0-3 2.650035 2.61053 2.68954 ZT4-7 2.8256249999999996 2.8256249999999996 2.8256249999999996 ZT8-11 2.878695 2.878695 2.878695 ZT12-15 0 0 0 ZT16-19 3.4023000000000003 3.4023000000000003 3.4023000000000003 ZT20-23 2.75155 2.75155 2.75155