condition mean min max ZT0-3 15.607545 15.607545 15.607545 ZT4-7 14.880000500000001 14.880000500000001 14.880000500000001 ZT8-11 17.3173275 17.3173275 17.3173275 ZT12-15 19.225187499999997 19.225187499999997 19.225187499999997 ZT16-19 17.2885115 17.2885115 17.2885115 ZT20-23 18.279940500000002 18.279940500000002 18.279940500000002