condition mean min max ZT0-3 5.6296225 5.566085 5.69316 ZT4-7 6.1633949999999995 6.1633949999999995 6.1633949999999995 ZT8-11 8.127965 8.127965 8.127965 ZT12-15 0 0 0 ZT16-19 8.29966 8.29966 8.29966 ZT20-23 9.046665 9.046665 9.046665