  In this paper, we propose a conjectural multiplicity formula for general
spherical varieties. For all the cases where a multiplicity formula has been
proved, including Whittaker model, Gan-Gross-Prasad model, Ginzburg-Rallis
model, Galois model and Shalika model, we show that the multiplicity formula in
our conjecture matches the multiplicity formula that has been proved. We also
give a proof of this multiplicity formula in two new cases.
