Rust Bucket Motor Credit Corporation (RBMCC), a subsidiary of Rust Bucket Motor, offered some securities for sale to the public on March 28, 2004. Under the terms of the deal, RBMCC promised to repay the owner of one of these securities $123,809 on March 28, 2039, but investors would receive nothing until then. Investors paid RBMCC $28,631 for each of these securities; so they gave up $28,631 on March 28, 2004 for the promise of a $123,809 payment in 2039.

Based on the $28,631 price, what rate was RBMCC paying to borrow money? (round 2 decimal places)