  Very deep galaxy surveys have revealed a considerably large population of
faint galaxies, which leads to the speculation that all distant objects are
moderately magnified by the gravitational lensing effects of galaxies (Fried
1997). In this letter, we present a simple estimate of the lensing amplitudes
by all galaxies up to redshift $z=2$ in terms of galaxy merging and answer the
question whether the sky is fully covered by the lensing cross-sections of
galaxies. It is shown that, as a result of the combination of the increase of
galaxy number density and the decrease of galaxy velocity dispersion with
lookback time, less than $\sim1/10$ of the sky to $z=2$ can be moderately
affected by galaxies acting as lenses with magnification $\mu>1.1$. This
conclusion is independent of the galaxy limiting magnitude. In other words, no
matter how high the surface number density of faint galaxies becomes, it is
unlikely that their lensing cross-sections of $\mu>1.1$ can cover the whole
sky.
