  We report the results of the statistical analysis of planetary signals
discovered in MOA-II microlensing survey alert system events from 2007 to 2012.
We determine the survey sensitivity as a function of planet-star mass ratio,
$q$, and projected planet-star separation, $s$, in Einstein radius units. We
find that the mass ratio function is not a single power-law, but has a change
in slope at $q \sim 10^{-4}$, corresponding to $\sim 20 M_{\oplus}$ for the
median host star mass of $\sim 0.6 M_{\odot}$. We find significant planetary
signals in 23 of the 1474 alert events that are well characterized by the
MOA-II survey data alone. Data from other groups are used only to characterize
planetary signals that have been identified in the MOA data alone. The
distribution of mass ratios and separations of the planets found in our sample
are well fit by a broken power-law model of the form $dN_{\rm pl}/(d{\rm log}
q\ d{\rm log} s) = A (q/q_{\rm br})^n s^m \, {\rm dex}^{-2}$ for $q > q_{\rm
br}$ and $dN_{\rm pl}/(d{\rm log} q\ d{\rm log} s) = A (q/q_{\rm br})^p s^m \,
{\rm dex}^{-2}$ for $q < q_{\rm br}$, where $q_{\rm br}$ is the mass ratio of
the break. We also combine this analysis with the previous analyses of Gould et
al. and Cassan et al., bringing the total sample to 30 planets. This combined
analysis yields $A = 0.61^{+0.21}_{-0.16}$, $n =-0.93\pm 0.13$, $m =
0.49_{-0.49}^{+0.47}$ and $p = 0.6^{+0.5}_{-0.4}$ for $q_{\rm br}\equiv
1.7\times 10^{-4}$. The unbroken power law model is disfavored with a $p$-value
of 0.0022, which corresponds to a Bayes factor of 27 favoring the broken
power-law model. These results imply that cold Neptunes are likely to be the
most common type of planets beyond the snow line.
