condition mean min max ZT0-3 21.149725 20.1098 22.18965 ZT4-7 2.206845 2.206845 2.206845 ZT8-11 3.697535 3.697535 3.697535 ZT12-15 0 0 0 ZT16-19 20.149050000000003 20.149050000000003 20.149050000000003 ZT20-23 3.4656700000000003 3.4656700000000003 3.4656700000000003