condition mean min max ZT0-3 2.780666 0.919684 6.0604700000000005 ZT4-7 5.328335 5.328335 5.328335 ZT8-11 3.1273150000000003 3.1273150000000003 3.1273150000000003 ZT12-15 2.3966575 2.01745 2.775865 ZT16-19 1.579515 1.579515 1.579515 ZT20-23 0.622566 0.622566 0.622566