Add 3.42m to all data values up to 1998 to refer to RLR (1976)
Add 3.431m to data values for 1999 to refer to RLR (1976)
Add 3.422m to data values for 2000 to refer to RLR (1976)
Add 3.417m to data values 2001 onwards to refer to RLR (1976)
RLR (1976) is 8.3m below Attached BM W 61
