condition mean min max ZT0-3 8.30862 8.30862 8.30862 ZT4-7 4.1646149999999995 4.1646149999999995 4.1646149999999995 ZT8-11 4.408085 4.408085 4.408085 ZT12-15 8.182245 8.182245 8.182245 ZT16-19 10.3048 10.3048 10.3048 ZT20-23 10.189039999999999 10.189039999999999 10.189039999999999