Add 6.745m to data values 1931-1959 to refer to RLR<br>Add 4.014m to data values 1960-1962 to refer to RLR<br>Add 2.186m to data values 1963-1972 to refer to RLR<br>Add 1.975m to data values 1973-1975 to refer to RLR<br>Add 4.495m to data values 1980 onwards to refer to RLR<br>RLR is 10.813m below primary benchmark NJ 9525 0590