condition mean min max ZT0-3 2.0120733333333334 2.0120733333333334 2.0120733333333334 ZT4-7 2.152375 2.152375 2.152375 ZT8-11 2.7821949999999998 2.7821949999999998 2.7821949999999998 ZT12-15 3.35435 3.35435 3.35435 ZT16-19 3.52462 3.52462 3.52462 ZT20-23 3.38476 3.38476 3.38476