condition mean min max ZT0-3 8.889794 8.889794 8.889794 ZT4-7 9.8340395 9.8340395 9.8340395 ZT8-11 8.149287000000001 8.149287000000001 8.149287000000001 ZT12-15 7.662019 7.662019 7.662019 ZT16-19 7.990454 7.990454 7.990454 ZT20-23 9.0722405 9.0722405 9.0722405