condition mean min max ZT0-3 21.105129015 20.878904509999998 21.33135352 ZT4-7 15.395799047499999 14.912040874999999 15.87955722 ZT8-11 15.4037827825 14.802556565 16.005009 ZT12-15 8.09254278125 5.8520758555 10.333009706999999 ZT16-19 6.3899643005 6.3324286385 6.4474999625 ZT20-23 5.3557077855 4.729643023 5.981772548