An amusing questtion, if intended as such, but... It is nearly impossible to respond with a a lot more detail. Most modern aircraft burn less fuel today than they did 30+ years ago, but details and computations do matter. Are you asking about flat gallons per trip - to where? Gallons/pounds/liters per seat or seat mile? Most numbers are far better today, and obviously the major carriers compute these details down to the 0.1% level 0 because it matters. And you question was???
