A major theme park is expanding the existing facility over a five-year period.

A major theme park is expanding the existing facility over a five-year period. The design phase will be completed one year after the contract is awarded. Major engineering drawings will be finalized two years after the design contract is awarded and construction will begin three years after the award of thedesign contract. New, unique ride technology will be used and an estimate will need to be developed to identify these costs that have no historical data.

Which of the following percent complete measurement techniques is best suited for long-term non-production accounts (such as overhead accounts)?