condition mean min max ZT0-3 18.683646 18.683646 18.683646 ZT4-7 20.425598 20.425598 20.425598 ZT8-11 17.0412775 17.0412775 17.0412775 ZT12-15 18.99954 18.99954 18.99954 ZT16-19 19.1006455 19.1006455 19.1006455 ZT20-23 19.6929835 19.6929835 19.6929835