Add 5.900m to data values 1934-1970 to refer to RLR<br>Add 6.000m to data values for 1971 to refer to RLR<br>Add 5.900m to data values 1972-1973 to refer to RLR<br>Add 6.200m to data values 1974 onwards to refer to RLR<br>RLR is 8.300m below primary benchmark DET 9