  In the framework of a specific scheme of the QCD sum rules for $S$-wave
levels of the heavy quarkonium, one derives an expression, relating the
energetic density of quarkonium states and universal characteristics in the
heavy quarkonium physics, such as the difference between the masses of a heavy
quark $Q$ and meson $(Q\bar q)$ and the number of heavy quarkonium levels below
the threshold of $(Q\bar Q) \to (Q\bar q) + (\bar Q q)$ decay.

High Energy Physics - Phenomenology