condition mean min max ZT0-3 5.210131666666666 4.237765 5.704125 ZT4-7 3.5634249999999996 3.5634249999999996 3.5634249999999996 ZT8-11 2.50459 2.50459 2.50459 ZT12-15 2.9953425 2.92606 3.064625 ZT16-19 3.1096 3.1096 3.1096 ZT20-23 3.7985949999999997 3.7985949999999997 3.7985949999999997