condition mean min max ZT0-3 7.7960449999999994 7.7960449999999994 7.7960449999999994 ZT4-7 7.0221 7.0221 7.0221 ZT8-11 8.434035 8.434035 8.434035 ZT12-15 6.200615 6.200615 6.200615 ZT16-19 7.621365 7.621365 7.621365 ZT20-23 7.843435 7.843435 7.843435