Add 5.9m to data values up to 1970 and 1972 to 1973 to refer to RLR (1972)
Add 6.0m to data for 1971 to refer to RLR (1972)
Add 6.2m to data values 1974and 1975to refer to RLR (1972)
RLR (1972) is 8.3m below BM DET 9
