Year Ending December 2012Year Ending December 2011Year Ending December 2010Revenues40,00035,00033,000Operating ExpensesSalaries15,00010,0009,000Maintenance and Repairs6,0009,00010,000Rental Expense2,5002,5002,500Depreciation2,0002,0002,000Fuel4,0003,5002,500Total Operating Expenses29,50027,00026,000Operating Income10,5008,0007,000Sales and Administrative Expenses6,0004,0003,000Interest Expense2,5002,0001,000Net Income2,0002,0003,000Above is a comparative income statement for Cecil, Inc. for the years 2010, 2011, and 2012.  Calculate the net-profit margin  for each of these years.  Comment on the profit margin trend.