for the unit pursuant to the emissions limitation requirements of this section applicable to the unit adjusted to reflect the unit 's annual average fuel consumption on a Btu basis of any three consecutive calendar years between 1980 and 1989 ( inclusive ) as elected by the owner or operator and ( B ) the number of allowances allocated for the unit pursuant to the emissions limitation requirements of this Provided , That the number of allowances allocated pursuant to this subsection shall not exceed an annual total of 40,000 .
The units of measurement were tracked over several calendar years .