condition mean min max ZT0-3 6.713536666666667 5.197115 7.68493 ZT4-7 4.06745 4.06745 4.06745 ZT8-11 5.226405 5.226405 5.226405 ZT12-15 12.563875000000001 11.920200000000001 13.207550000000001 ZT16-19 11.2623 11.2623 11.2623 ZT20-23 10.05726 10.05726 10.05726