  Core-collapse supernova explosions expose the structure and environment of
massive stars at the moment of their death. We use the global fitting technique
of Pejcha & Prieto (2015a,b) to estimate a set of physical parameters of 19
normal Type II SNe, such as their distance moduli, reddenings, $^{56}$Ni masses
$M_{\rm Ni}$, and explosion energies $E_{\rm exp}$ from multicolor light curves
and photospheric velocity curves. We confirm and characterize known
correlations between $M_{\rm Ni}$ and bolometric luminosity at 50 days after
the explosion, and between $M_{\rm Ni}$ and $E_{\rm exp}$. We pay special
attention to the observed distribution of $M_{\rm Ni}$ coming from a joint
sample of 38 Type~II SNe, which can be described as a skewed-Gaussian-like
distribution between $0.005~M_{\odot}$ and $0.280~M_{\odot}$, with a median of
$0.031~M_{\odot}$, mean of $0.046~M_{\odot}$, standard deviation of
$0.048~M_{\odot}$ and skewness of $3.050$. We use two-sample Kolmogorov-Smirnov
test and two-sample Anderson-Darling test to compare the observed distribution
of $M_{\rm Ni}$ to results from theoretical hydrodynamical codes of
core-collapse explosions with the neutrino mechanism presented in the
literature. Our results show that the theoretical distributions obtained from
the codes tested in this work, KEPLER and Prometheus Hot Bubble, are compatible
with the observations irrespective of different pre-supernova calibrations and
different maximum mass of the progenitors.
