Answer
${\bf 1.22\%}$
Work Step by Step
We know that the probability of tunneling is given by
$$
P_{\text{tunnel}} = e^{-2w\eta}\tag 1
$$
Where $ w $ is the width of the barrier, and $\eta$ is the penetration distance which is given by:
$$
\eta = \frac{\hbar}{\sqrt{2m(U_0 - E)}}
$$
where $ U_0 - E = 1.0\;\rm MeV$
Plug the known;
$$
\eta = \frac{(1.05 \times 10^{-34})}{\sqrt{2(1.67\times 10^{-27} )(1.0\times 10^6\times 1.6 \times 10^{-19} )}}=\bf 4.54 \times 10^{-15}\;\rm m
$$
Substitute all the known into (1);
$$
P_{\text{tunnel}} = e^{-2(10\times 10^{-15}) / (4.54 \times 10^{-15})}
$$
$$
P_{\text{tunnel}}=0.0122 \approx \color{red}{\bf 1.22\%}
$$
