condition mean min max ZT0-3 11.358633333333334 7.3014 13.877749999999999 ZT4-7 5.934609999999999 5.934609999999999 5.934609999999999 ZT8-11 8.64705 8.64705 8.64705 ZT12-15 18.902250000000002 17.4613 20.343200000000003 ZT16-19 22.7316 22.7316 22.7316 ZT20-23 23.27995 23.27995 23.27995