user: ### NOW ANSWER:
Question: What was the rural % where the source estimate was census and the urban % was larger than 57?
Columns: ['Year (January)', "Population ('000)", 'Rural, %', 'Urban, %', 'Source']
Types: ['real', 'real', 'real', 'real', 'text']
Sample row: [1939.0, 6081.0, 72.0, 28.0, 'census']
SQL:

assistant: SELECT SUM("Rural, %") FROM "Table" WHERE "Source" = 'estimate' AND "Urban, %" > 57.0;