condition mean min max ZT0-3 6.0917625 6.0900549999999996 6.09347 ZT4-7 8.432504999999999 8.432504999999999 8.432504999999999 ZT8-11 8.667455 8.667455 8.667455 ZT12-15 0 0 0 ZT16-19 8.120295 8.120295 8.120295 ZT20-23 8.328125 8.328125 8.328125