condition mean min max ZT0-3 21.287675 20.324849999999998 22.2505 ZT4-7 14.69505 14.69505 14.69505 ZT8-11 8.94567 8.94567 8.94567 ZT12-15 0 0 0 ZT16-19 0.9204185 0.9204185 0.9204185 ZT20-23 3.2992600000000003 3.2992600000000003 3.2992600000000003