  Dynamical searches find central dark objects - candidate supermassive black
holes (BHs) - in at least 34 galaxies. The demographics of these objects lead
to the following conclusions: (1) BH mass correlates with the luminosity of the
bulge component of the host galaxy, albeit with considerable scatter. The
median BH mass fraction is 0.15 % of the mass of the bulge. The quartiles are
0.09 % and 0.7 %. (2) BH mass correlates with the mean velocity dispersion of
the bulge component inside its effective radius, i.e., with how strongly the
bulge stars are gravitationally bound to each other. For the best BH mass
determinations, the scatter is consistent with the measurement errors. (3) BH
mass correlates with the luminosity of the high-density central component in
disk galaxies independent of whether this is a real bulge (a mini-elliptical)
or a "pseudobulge" (believed to form via inward transport of disk material).
(4) BH mass does not correlate with the luminosity of galaxy disks. If pure
disks contain BHs (and observations of active nuclei argue that some do), then
their BH mass fractions are much smaller than the canonical 0.15 % for bulges.
  These results lead to the following conclusions: (A) Present observations
show no dependence of BH mass on the details of whether BH feeding happens
rapidly during a collapse or slowly via secular evolution of the disk. (B) The
above results increasingly support the hypothesis that the major events that
form a bulge or elliptical galaxy and the main growth phases of its BH -- when
it shone as an active nucleus -- were the same events.
