condition mean min max ZT0-3 2.492745 2.492745 2.492745 ZT4-7 3.53367 3.53367 3.53367 ZT8-11 14.68515 14.68515 14.68515 ZT12-15 37.3337 37.3337 37.3337 ZT16-19 15.489349999999998 15.489349999999998 15.489349999999998 ZT20-23 2.43621 2.43621 2.43621