condition mean min max ZT0-3 9.162754 9.162754 9.162754 ZT4-7 8.7158725 8.7158725 8.7158725 ZT8-11 8.299806 8.299806 8.299806 ZT12-15 9.0429035 9.0429035 9.0429035 ZT16-19 8.3575675 8.3575675 8.3575675 ZT20-23 9.0607135 9.0607135 9.0607135