Eulerian and Hamiltonian Graphs · Hard problem

The wheel graph $W_5$ has a hub vertex joined to all five rim vertices of a $5$-cycle $1\text{-}2\text{-}3\text{-}4\text{-}5\text{-}1$. Counting two cycles as the same whenever they use the same set of edges, how many distinct Hamiltonian cycles does $W_5$ have?