condition mean min max ZT0-3 10.860991 10.860991 10.860991 ZT4-7 9.70544 9.70544 9.70544 ZT8-11 9.797298999999999 9.797298999999999 9.797298999999999 ZT12-15 11.1863915 11.1863915 11.1863915 ZT16-19 11.2926675 11.2926675 11.2926675 ZT20-23 11.2298335 11.2298335 11.2298335