Why not simply insert a DATE field (or a CREATEDATE field if it is a template)
{ DATE \@ "yyyy" } or { CREATEDATE \@ "yyyy" } ? This will always show the year (or in the case of the latter the year the document was created.
To insert a DocProperty field
Code:
Selection.Fields.Add Range:=Selection.Range, Type:=wdFieldDocProperty, Text:="Annee", PreserveFormatting:=False