The amount of conventional hydroelectric power (in quadrillion Btu) consumed from 1990 to 1997 can be modeled by P = -0.004t³ + 0.082t² - 0.268t + 3.206, where t is the number of years since 1990. For the same years, the U.S. population (in millions) can be modeled by P = 2.61t + 247, where t is the number of years since 1990. Find a function for the average amount of energy consumed by each person from 1990 to 1997. What was the per capita consumption of conventional power in 1992?