Some industry data is readily available online. However, many data sets are proprietary and expensive to purchase. Below are some trade publications and freely-available online sites with select industry data.
Film Daily Yearbook (1918-1969) Trade publication covering the film industry. Indexing is sparse, but the early statistical information is worth the work.
Box Office Mojo: Commercial website claims to offer "the most comprehensive box office tracking available online."
Information on the television and movie industries. Includes historical box office information, company organization charts and information on films and TV shows currently in production.