condition mean min max ZT0-3 8.446746 8.446746 8.446746 ZT4-7 8.173216499999999 8.173216499999999 8.173216499999999 ZT8-11 8.2667635 8.2667635 8.2667635 ZT12-15 8.446746 8.446746 8.446746 ZT16-19 8.5594615 8.5594615 8.5594615 ZT20-23 8.8582375 8.8582375 8.8582375