How can summarize item in a listview

I have the following 2 field in a grid
GRID
====
GroupField   TotalField
AAA            1
BBB            1
CCC            1
AAA            1
BBB            2
CCC            1
AAA            1
BBB            1
================
Now i need to provide a summary in a listview as follows

GroupField   TotalField
AAA             3
BBB            4
CCC            2
==========================

I have done the following


Private sub SetupListview

      with lvw.ColumnHeaders
          .Clear
          .Add, "Grp","Group,2000
            .Add, "Ttl","Total,2000
 
      end with
end sub

Private sub PopulateListView(Byval strGroup as string,intValue as integer)
      dim li as listItem
        dim liKey as string

liKey="k" & StrGroup
      if lvw.listitems.count > 0 Then
      

            for each li in lvw.listitems
                  if li.text=strGroup then
                        li.subItems(1)=IntValue + 1
                  else
                        SET LI=LVW.ListItems.Add(,likey,strGroup)
                        li.subItems(1)=IntValue
                  end if
            next
      else
            
            SET LI=LVW.ListItems.Add(,likey,strGroup)
            li.subItems(1)=IntValue
      end if

end sub