Date and Time Stamp for Last Activity in Range

I know this is retarded basic, but I'm a VBA noob and trying to create a date/time stamp if anything in columns B:O are changed. This code works great if i wanted to go A:O, but I don't know how to fix it. Thanks for the help.

Private Sub Worksheet_Change(ByVal Target As Range)
    If Target.Column <= 15 Then
        Application.EnableEvents = False
        Cells(Target.Row, 16).Value = Date + Time
        Application.EnableEvents = True
    End If
End Sub