question: What is the August 15, 2012 population when the  population density of 2012 is 307?
answer: SELECT MAX(population_august_15), _2012 FROM table_12496904_1 WHERE population_density_2012__km_2__ = 307
context: CREATE TABLE table_12496904_1 (_2012 VARCHAR, population_august_15 INTEGER, population_density_2012__km_2__ VARCHAR)