condition mean min max ZT0-3 4.083505 2.4629649999999996 5.876815000000001 ZT4-7 2.079395 2.079395 2.079395 ZT8-11 3.427805 3.427805 3.427805 ZT12-15 7.533415 7.25666 7.810169999999999 ZT16-19 6.84377 6.84377 6.84377 ZT20-23 7.62514 7.62514 7.62514