condition mean min max ZT0-3 2.6637950000000004 2.6637950000000004 2.6637950000000004 ZT4-7 2.173505 2.173505 2.173505 ZT8-11 1.6141450000000002 1.6141450000000002 1.6141450000000002 ZT12-15 1.9777550000000002 1.9777550000000002 1.9777550000000002 ZT16-19 2.467735 2.467735 2.467735 ZT20-23 2.6754 2.6754 2.6754