condition mean min max ZT0-3 2.170214 0.6804 3.660028 ZT4-7 19.94415 19.94415 19.94415 ZT8-11 6.8565000000000005 6.8565000000000005 6.8565000000000005 ZT12-15 0 0 0 ZT16-19 6.547915 6.547915 6.547915 ZT20-23 7.967105 7.967105 7.967105