what is the crude birth rate (per 1000) when the crude death rate (per 1000) is less than 6.2, the average population (x1000) is larger than 2,770 and the natural change (per 1000) is 17.2?
SELECT SUM Crude birth rate (per 1000) FROM table WHERE Crude death rate (per 1000) < 6.2 AND Average population (x 1000) > 2,770 AND Natural change (per 1000) = 17.2