condition mean min max ZT0-3 7.617291 7.617291 7.617291 ZT4-7 7.7985555 7.7985555 7.7985555 ZT8-11 7.7859645 7.7859645 7.7859645 ZT12-15 7.9336535 7.9336535 7.9336535 ZT16-19 7.188103 7.188103 7.188103 ZT20-23 6.895173 6.895173 6.895173