Add 6.735m to data values 1949-1969 to refer to RLR<br>Add 6.491m to data values for 1970 to refer to RLR<br>Add 6.411m to data values for 1971 to refer to RLR<br>Add 6.413m to data values 1972-1975 to refer to RLR<br>Add 6.412m to data values 1976-1977 to refer to RLR<br>Add 6.414m to data values 1978-1979 to refer to RLR<br>Add 6.413m to data values 1980-1983 to refer to RLR<br>Add 6.417m to data values 1984-1992 to refer to RLR<br>RLR is 9.100m below primary benchmark BM4