Operating profit margin is “a measurement of what proportion of a company's revenue is left over after paying for variable costs of production such as wages, raw materials, etc.” (Operating Profit Margin, 2015) In 2008, the firms gain the highest proportion at 0.087. It implied that the company made the highest profit that minus costs of production. In 2009, the proportion is greatly declined to 0.0344, and it continued to decrease to 0.027 in 2010. In 2010, the smallest proportion, yet it could climbed up to 0.087 in 2012 which is the largest proportion in 9 years historically. In 2015, the proportion is at 0.07, so the latest operating profit margin is better.