The number(s) you are looking for vary quite a bit with aircraft configuration. If you only want ballpark figures. the tail download might be as high as 35 percent weight for full flaps, forward CG limit and approach speed.
For a clean aircraft in cruise at aft CG limit the load might be as low as 3 to 5 percent weight depending on the stability designed in. Aircraft with fuel tanks in the tail will be at the lower end of this range.
All that for level flight as you specified in the OP, and by "elevator" I assume you mean tail.