condition mean min max ZT0-3 7.5924499999999995 7.5924499999999995 7.5924499999999995 ZT4-7 6.005575 6.005575 6.005575 ZT8-11 6.609585 6.609585 6.609585 ZT12-15 8.32485 8.32485 8.32485 ZT16-19 9.907070000000001 9.907070000000001 9.907070000000001 ZT20-23 8.593805 8.593805 8.593805