condition mean min max ZT0-3 3.377555 3.377555 3.377555 ZT4-7 2.775045 2.775045 2.775045 ZT8-11 2.5495 2.5495 2.5495 ZT12-15 2.389215 2.389215 2.389215 ZT16-19 3.789295 3.789295 3.789295 ZT20-23 3.176965 3.176965 3.176965