My car is also camry, 91, 230K, in the summer sometimes it needs 7.5L/100km, sometimes 8.5L/100km, now, almost 9-10L/100kM(winter). Normally when the gas warning light is on you still have 10L in your car. So you must meausre as what I told you. But it is better to use the same gas station, and each time put the gas gun at the same depth.
Camry is a good car, at least mine is.