condition mean min max ZT0-3 6.930649 6.930649 6.930649 ZT4-7 7.8998115 7.8998115 7.8998115 ZT8-11 7.4482685 7.4482685 7.4482685 ZT12-15 7.5799395 7.5799395 7.5799395 ZT16-19 7.263793 7.263793 7.263793 ZT20-23 7.182281 7.182281 7.182281