condition mean min max ZT0-3 8.21105 8.21105 8.21105 ZT4-7 8.82863 8.82863 8.82863 ZT8-11 8.88984 8.88984 8.88984 ZT12-15 8.949883333333334 8.949883333333334 8.949883333333334 ZT16-19 8.773200000000001 8.773200000000001 8.773200000000001 ZT20-23 8.442070000000001 8.442070000000001 8.442070000000001