Schema.org is a vocabulary "for describing the kind of entities the most common web applications need" (source). But which entities would that be? Intuitively I’d say the most common entities are organizations (including companies, clubs, etc.), persons (authors, team members, etc.), products, and creative works (stories, movies, images, music, etc.).
Is there a data source that can give insight into which kind of entities appear on web pages how often? The source should make clear if it’s about entities the page is about, or entities that are described, or entities that are mentioned.
(The data source should of course not make use of Schema.org or some other vocabulary, because that would bias the results: you can only mark up content with existing types, but one of my goals is to find types that are missing.)
To be clear, I’m interested in categories of entities (e.g., person, book, organization), not instances (e.g., Bazzel Baz, The Lord of the Rings, Internet Archive).
Ideally with more specific categories, e.g. musician/author/CEO/etc. instead of person, and restaurant/political party/company/etc. instead of organization, etc.