Add 5.911m to data values up to 1995 to refer to RLR (1976)
Add5.894m to data values 1996-1997 to refer to RLR (1976)
Add 5.889m to data values 1998 onwards to refer to RLR (1976)
RLR (1976) is 10.389m below Attached BM (i)
