Listbox

Question

hi Im sending strings to a listbox,

How do i get a count of a specific string,

                               Listbox test = new Listbox();

                                if (sEtag[0] == 'E' || sEtag == "F001" || sEtag == "F000"||sEtag=="A083")
                                {
                                    test.Items.Add(sEtag.ToString());
                                }

                               how do i get the count of one of those four strings from the listbox?