condition mean min max ZT0-3 8.948263 8.948263 8.948263 ZT4-7 10.290631 10.290631 10.290631 ZT8-11 9.5687115 9.5687115 9.5687115 ZT12-15 8.909196999999999 8.909196999999999 8.909196999999999 ZT16-19 9.7022245 9.7022245 9.7022245 ZT20-23 9.215071 9.215071 9.215071