condition mean min max ZT0-3 8.175259 8.175259 8.175259 ZT4-7 10.1323615 10.1323615 10.1323615 ZT8-11 8.091298 8.091298 8.091298 ZT12-15 8.0954795 8.0954795 8.0954795 ZT16-19 7.965196 7.965196 7.965196 ZT20-23 8.145921 8.145921 8.145921