The Camino Real Landfill was required to install a plastic liner to prevent leachate from migrating into the groundwater. The fill area was 50,000 m² and the installed liner cost was $8 per m². In order to recover the investment, the owner charges to unload at the rates of $10 per pick-up, $25 per dumptruck, and $70 per compactor-truck load. The fill area is adequate for 4 years. If the annual traffic is estimated to be 2500 pick-up loads, 650 dumptruck loads, and 1200 compactor-truck loads, what rate of return will the landfill owner make on the investment?