condition mean min max ZT0-3 17.242573 17.242573 17.242573 ZT4-7 16.543149 16.543149 16.543149 ZT8-11 18.726236 18.726236 18.726236 ZT12-15 19.395466 19.395466 19.395466 ZT16-19 16.976060500000003 16.976060500000003 16.976060500000003 ZT20-23 16.3785345 16.3785345 16.3785345