condition mean min max ZT0-3 4.363716666666667 1.99035 6.0271799999999995 ZT4-7 2.48628 2.48628 2.48628 ZT8-11 2.3127050000000002 2.3127050000000002 2.3127050000000002 ZT12-15 4.61336 4.419095 4.807625 ZT16-19 6.1144099999999995 6.1144099999999995 6.1144099999999995 ZT20-23 8.93633 8.93633 8.93633