  One of the first finding concerning the superconducting (SC) density $n_{\rm
sc}$ in cuprates was their small magnitudes that revealed the importance of
phase fluctuations. More recently, measurements in a variety of overdoped
cuprates indicate that it is also much smaller than expected from BCS theories
and falls smoothly to zero as doping is increased. We explain these
observations by an electronic phase separation theory with a Ginzburg-Landau
potential $V_{\rm GL}$ that produces alternating charge domains whose
fluctuations lead to localized SC order parameters that are connected by
Josephson coupling $E_{\rm J}$. The average ${\left <E_{\rm J}( p,T)\right>}$
is proportional to the local superfluid phase stiffness $\rho_{\rm sc} \propto
n_{\rm sc}$. The fraction of condensed carriers decreases in the overdoped
region due to the weakening of $V_{\rm GL}$. The results agreed with $\rho_{\rm
sc}(p)$ vs. $T_{\rm c}(p)$ and the Drude-like peak measurements.
