How much do you know about frozen food?

Americans spend more than $9 billion a year on frozen dinners, according to market research firm Euromonitor. That’s a whole lot of lasagna, pizza, macaroni and cheese, and many, many other heat-and-eat entrees. The clear brand leader in the frozen dinner category is Stouffer’s, which has a larger share of the market than its three closest competitors combined. But the company isn’t as dominant as it first appears -- three of the other brands in the top five are owned by ConAgra Foods, and their combined market share come closes to Stouffer’s.This is not an industry that shows wild swings; revenue varies only slightly from year to year. Euromonitor numbers do show there has been a small drop-off from 2009, when sales peaked at $9.2 billion. Here are the top brands.