condition mean min max ZT0-3 4.274115 4.274115 4.274115 ZT4-7 2.79582 2.79582 2.79582 ZT8-11 4.374805 4.374805 4.374805 ZT12-15 6.755975 6.755975 6.755975 ZT16-19 4.383575 4.383575 4.383575 ZT20-23 6.67422 6.67422 6.67422