It depends on the year.
to Sep80, 3.90-2.30-1.41-1.00 R3.66
Oct80-Aug83, 3.91-2.32-1.42-1.00 R3.78
Sep83 on, 4.23-2.36-1.49-1.00 R4.10

All had a 3.69 diff ratio.