condition mean min max ZT0-3 5.831935 5.831935 5.831935 ZT4-7 6.847860000000001 6.847860000000001 6.847860000000001 ZT8-11 1.164583 1.164583 1.164583 ZT12-15 1.2989465 1.2989465 1.2989465 ZT16-19 2.242085 2.242085 2.242085 ZT20-23 3.2655649999999996 3.2655649999999996 3.2655649999999996