Add 4.08m to data values up to 1980 to refer to RLR(1964)
Add 3.639m to data values 1981-1983 to refer to RLR(1964)
Add 2.236m to data values for 1984 to refer to RLR(1964)
Add 3.899m to data values 1985 onwards to refer to RLR(1964)
RLR (1964) is 11.7m below TGBM SW 4676 2855
