condition mean min max ZT0-3 23.7177 23.7177 23.7177 ZT4-7 20.6936 20.6936 20.6936 ZT8-11 20.28925 20.28925 20.28925 ZT12-15 21.3617 21.3617 21.3617 ZT16-19 30.95005 30.95005 30.95005 ZT20-23 26.537999999999997 26.537999999999997 26.537999999999997