condition mean min max ZT0-3 6.79 6.79 6.79 ZT4-7 6.505 6.505 6.505 ZT8-11 6.115 6.115 6.115 ZT12-15 5.291111111 5.291111111 5.291111111 ZT16-19 4.241111111 4.241111111 4.241111111 ZT20-23 4.757777778 4.757777778 4.757777778