condition mean min max ZT0-3 18.700825000000002 18.52085 18.8808 ZT4-7 15.8488 15.8488 15.8488 ZT8-11 8.004480000000001 8.004480000000001 8.004480000000001 ZT12-15 0 0 0 ZT16-19 22.03715 22.03715 22.03715 ZT20-23 31.5024 31.5024 31.5024