  We consider the incompressible 2D Navier-Stokes equations with periodic
boundary conditions driven by a deterministic time periodic forcing and a
degenerate stochastic forcing. We show that the system possesses a unique
ergodic periodic invariant measure which is exponentially mixing under a
Wasserstein metric. We also prove the weak law of large numbers for the
continuous time inhomogeneous solution process. In addition, we obtain the weak
law of large numbers and central limit theorem by restricting the inhomogeneous
solution process to periodic times. The results are independent of the strength
of the noise and hold true for any value of viscosity with a lower bound
$\nu_1$ characterized by the Grashof number $G_1$ associated with the
deterministic forcing. In the laminar case, there is a larger lower bound
$\nu_2$ of the viscosity characterized by the Grashof number $G_2$ associated
with both the deterministic and random forcing. We prove that in this laminar
case, the system has trivial dynamics for any viscosity larger than $\nu_2$ by
demonstrating the existence of a unique globally exponentially stable random
periodic solution that supports the unique periodic invariant measure.
