condition mean min max ZT0-3 3.4271555 1.7402514999999998 5.353365 ZT4-7 1.5398435 1.5398435 1.5398435 ZT8-11 0.546387 0.546387 0.546387 ZT12-15 4.1768600000000005 4.027555 4.3261650000000005 ZT16-19 2.25809665 2.25809665 2.25809665 ZT20-23 9.48433 9.48433 9.48433