  The phenomenon of centrality scaling in the high-\pt spectra of $\pi^0$
produced in Au-Au collisions at $\sqrt s=200$ GeV is examined in the framework
of relating fractional energy loss to fractional centrality increase. A new
scaling behavior is found where the scaling variable is given a power-law
dependence on $N_{\rm part}$. The exponent $\gamma$ specifies the fractional
proportionality relationship between energy loss and centrality, and is a
phenomenologically determined number that characterizes the nuclear suppression
effect. The implication on the parton energy loss in the context of
recombination is discussed.
