I don't think that we will ever know any statistics on this because it is a matter of the internal forum, and consequently there is no official certification, anywhere.  

WE do know that there are a number of Dioceses and Archdioceses where the local Ordinaries have publicly declared that there will be no readmittance to Communion to divorced and remarried Catholics who have not obtained a public declaration of nullity for the previous attempt at marriage by an ecclesiastical Tribunal competent to declare such nullity.