  Consider the non-compact billiard in the first quandrant bounded by the
positive $x$-semiaxis, the positive $y$-semiaxis and the graph of $f(x) =
(x+1)^{-\alpha}$, $\alpha \in (1,2]$. Although the Schnirelman Theorem holds,
the quantum average of the position $x$ is finite on any eigenstate, while
classical ergodicity entails that the classical time average of $x$ is
unbounded.
