Private Sub Worksheet_Change(ByVal Target As Range)
Dim coul&, colonne As Range, n&, c As Range
coul = [A1].Interior.Color
Application.EnableEvents = False 'désactive les évènements
For Each colonne In [C4:G21].Columns 'plage à adapter
n = 0
For Each c In colonne.Cells
If c.DisplayFormat.Interior.Color = coul Then n = n + 1
Next c
colonne.Cells(-1) = n
Next colonne
Application.EnableEvents = True 'réactive les évènements
End Sub