condition mean min max ZT0-3 32.162952 32.162952 32.162952 ZT4-7 30.3053595 30.3053595 30.3053595 ZT8-11 28.6668565 28.6668565 28.6668565 ZT12-15 27.766355 27.766355 27.766355 ZT16-19 26.2100795 26.2100795 26.2100795 ZT20-23 32.27413 32.27413 32.27413