Calculating Rates of Return

Assume that in 2015, the first edition of a comic book was sold at auction for $2,310,000. The comic book was originally sold in 1938 for $.05.

For this to have been true, what was the annual increase in the value of the comic book? (Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.)

Annual increase             %