  \item[Purpose] We suppose that the IYR(m) depends on the neutron-skin
thickness ($\delta_{np}$) of the projectile, and check the idea of whether the
neutron-skin thickness effects can fully explain the systematic dependence of
the IYR(m). \item[Methods] A modified statistical abrasion-ablation model is
used to calculate the reactions induced by projectiles of three series.
\item[Results] The IYR(m) shows a distribution of a linear part in the
small-$x$ fragments, and a nonlinear part in the large-$x$ fragments. The
linear part of IYR(m) is fitted. (1) In the calcium isotopic reactions, the
IYR(m) depends on the isospin or the volume of the projectile, but
$\delta_{np}$ greatly influences the nonlinear part of the IYR(m). The IYR(m)
does not depend on the colliding source in reactions of small $b_{\mbox{max}}$
for the nonneutron-rich projectiles, and does not depend on the collision
sources in reactions by the neutron-rich projectiles; (2) In reactions of the
$A = 45$ isobars, though IYR(m) depends on the isospin of projectile, IYR(m)
shows small dependence on isospin if $\delta_{np} > 0$; (3) In the reactions of
projectiles having similar $\delta_{np}$, the IYR(m) in the small mass
fragments show no dependence on the volume and the isospin of the projectile
when the mass of the projectile is relatively large. Specially, the dependence
of IYR(m) on the mass of the isospin of the projectile vanishes when
$\delta_{np}\sim0.02$fm. \item[Conclusions] The linear and nonlinear parts of
the IYR(m) are governed by the core and the surface (skin) of the projectile,
respectively. The neutron-skin effects can well explain the systematic
dependence of the IYR(m).
