These numbers are from Wikipedia

Business

In the United States, consumers spent about US$110 billion on fast food in 2000 (which increased from US$6 billion in 1970).The National Restaurant Association forecasted that fast food restaurants in the U.S. would reach US$142 billion in sales in 2006, a 5% increase over 2005. In comparison, the full-service restaurant segment of the food industry is expected to generate $173 billion in sales. Fast food has been losing market share to fast casual dining restaurants, which offer more robust and expensive cuisines.

Employment

According to the U.S. Bureau of Labor Statistics, about 4.1 million U.S. workers are employed in food preparation and serving (including fast food) as of 2010. The BLS’s projected job outlook expects average growth and excellent opportunity as a result of high turnover. However, in April 2011, McDonald’s hired approximately 62,000 new workers and received a million applications for those positions—an acceptance rate of 6.2%. The median age of workers in the industry in 2013 was 28.