  We present a new and simple method of calculating the occupation probability
of the number of total harmonic-oscillator quanta for a microscopic
cluster-model wave function. Examples of applications are given to the recent
calculations including $\alpha+n+n$-model for $^6$He, $\alpha+t+n+n$-model for
$^9$Li, and $\alpha+\alpha+n$-model for $^9$Be as well as the classical
calculations of $\alpha+p+n$-model for $^6$Li and $\alpha+\alpha+\alpha$-model
for $^{12}$C. The analysis is found to be useful for quantifying the amount of
excitations across the major shell as well as the degree of clustering. The
origin of the antistretching effect is discussed.
