Business Sources

Read the market share data carefully.  Often, the data is old or on only a segment of the market.

Marketline Advantage  Search for industry. Each report gives market size, share and segmentation data plus detailed analysis and company information within the industry (leading  companies, Five Forces Analysis)

Mintel  Reports on different markets focusing on the consumer.  Includes market drivers, marketing strategies, market size and demographics, forecast.  You must register but it's free.