condition mean min max ZT0-3 5.334432 1.2197710000000002 7.8096499999999995 ZT4-7 2.384005 2.384005 2.384005 ZT8-11 2.671675 2.671675 2.671675 ZT12-15 5.7749250000000005 3.081645 8.468205000000001 ZT16-19 9.116249999999999 9.116249999999999 9.116249999999999 ZT20-23 11.17165 11.17165 11.17165