Let the function $$f$$ be defined by $$f(x) = e^{-x}$$. Consider the following statements regarding the average value of $$f$$ on the interval $$[0, L]$$, where $$L > 0$$.

I. The average value is given by the expression $$\frac{1}{L}\int_0^L e^{-x}dx$$.

II. The average value is always less than $$e^{-L/2}$$.

III. As $$L$$ approaches infinity, the average value approaches 0.

Which of the statements above is/are true?