An interesting question, although it looks like you forgot to mention the Intended Route. Ahem, sir, that does make a huge difference! As only a a wild-assed guess, if you are thinking long-haul or x-ponding with today's twins, I'd WAG it in the 60% range. As you should know, it varies a LOT, always dependent upon the aircraft type, the load and the route.
After rereading your question, I'm not sure that I understand your objective. Can you restate your basic question? In extremely simple terms, yes, today's aircraft load less fuel than in your experience. Most burn two engines, not four and are more efficient. Gross loads vary a lot as does the weather. Please restate you question, including what you Really want to know, and I'm sure that someone will provide a few answers. Good luck, sir. Yup, got to be a bit more specific.
