condition mean min max ZT0-3 5.8537 5.8537 5.8537 ZT4-7 3.891985 3.891985 3.891985 ZT8-11 4.18502 4.18502 4.18502 ZT12-15 6.01474 6.01474 6.01474 ZT16-19 7.010820000000001 7.010820000000001 7.010820000000001 ZT20-23 7.155315 7.155315 7.155315