28. The Consumer Price Index for a year is the annual average of the Consumer Price Index for Canada established by Statistics Canada under the Statistics Act (Revised Statutes of Canada, 1985, chapter S-19) for each of the twelve months of the year for which the index is computed.
Where the annual average computed under the first paragraph or the percentage computed under section 27 has more than three decimals, only the first three decimals are kept and the third decimal is increased by a unit if the fourth decimal is 5 or over.