VBA To Count Occurrences On A List And Assign Number

I have found ways to count cells but what I am trying to do is in column F I have a list of meeting topics, and sometimes these repeat in a year. in my drop down menu I have all of them listed however my supervisor wants me to add a count after the meeting number in the 1_1X format where x is the number of times a topic has been used.

The output will be added to my macro here

Code:

Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)

Dim y As String
Dim z As String
Dim b as Integer

If Target.Cells.Count > 1 Then Exit Sub
If Intersect(Target, Range("MEETINGNUMBER")) Is Nothing Then Exit Sub

[Code] .......