condition mean min max ZT0-3 2.7666666666666666 2.10541 3.407785 ZT4-7 1.610315 1.610315 1.610315 ZT8-11 2.3306950000000004 2.3306950000000004 2.3306950000000004 ZT12-15 3.2964575 2.9497999999999998 3.643115 ZT16-19 3.56345 3.56345 3.56345 ZT20-23 3.6196 3.6196 3.6196