The following table shows the total dollar amount of sales in 2018 for the four largest firms in the cupcake industry. Total industry sales in 2018 were $875,000. Firm Sales in 2018 The Cupcakery $275.000 Sweet Shop, Inc. $150,000 Little Cake Co. $125,000 City Cupcakes $75,000 All other firms in the industry combined $250,000 Calculate the four-firm concentration ratio for the cupcake industry. What does this ratio tell us