COMPUTATION OF THE INTEREST RATE
The formula for the computation of the rate of interest for the reference year is the following:
iy = ( (1 + Ty-1 ) ( 1 + Ty-2 ) ( 1 + Ty-3 ) ) 1/3 - 1
where:
Ty-1: rate of return for the year preceding the reference year
Ty-2: rate of return for the year occurring 2 years before the reference year
Ty-3: rate of return for the year occurring 3 years before the reference year