An ecological monitoring program tracked the population of breeding pairs of Magellanic penguins (Spheniscus magellanicus\textit{Spheniscus magellanicus}Spheniscus magellanicus) in a coastal colony over several decades.
In 1989, the number of breeding pairs recorded was 18,300. In 2023, the number of breeding pairs recorded was 4,120.
Calculate the mean annual decrease in the population of individual penguins in this colony between 1989 and 2023. Assume each breeding pair consists of two individual birds. Show your working. Give your answer to three significant figures and include the units.
