condition mean min max ZT0-3 8.446746 8.446746 8.446746 ZT4-7 9.069773 9.069773 9.069773 ZT8-11 8.1072805 8.1072805 8.1072805 ZT12-15 7.9529565 7.9529565 7.9529565 ZT16-19 9.1323965 9.1323965 9.1323965 ZT20-23 7.9808235 7.9808235 7.9808235