condition mean min max ZT0-3 5.903135 5.903135 5.903135 ZT4-7 5.584465 5.584465 5.584465 ZT8-11 6.06684 6.06684 6.06684 ZT12-15 6.504635 6.504635 6.504635 ZT16-19 7.432729999999999 7.432729999999999 7.432729999999999 ZT20-23 6.34378 6.34378 6.34378