condition mean min max ZT0-3 7.646142 7.646142 7.646142 ZT4-7 7.9458035 7.9458035 7.9458035 ZT8-11 7.439794 7.439794 7.439794 ZT12-15 7.6441775 7.6441775 7.6441775 ZT16-19 7.621378 7.621378 7.621378 ZT20-23 7.957037999999999 7.957037999999999 7.957037999999999