In this paper the integer
valued ω-index theory parameterized by all ω on the unit circle for paths in the
symplectic group Sp(2n) is established. Based on this index theory, the Bott formula
of the Maslov-type index theory for iterated paths in Sp(2n) is estalished, the mean
index for periodic solutions of Hamiltonian systems is defined, and the increasing
estimate of the iterated Maslov-type index in terms of the mean index is
proved.