My best - or worst - I should say, guess is that everything currently free on Box Office Mojo - other then the daily overview chart - might soon be hidden behind the IMDbPro pay wall.
Here is the opening of the article at The Wrap:
Box Office Mojo Absorbed Into IMDb.com
The site has been quietly redirected to its parent companyBox Office Mojo website has been shut down, as the site currently redirects to IMDb.
Box Office Mojo was acquired by IMDb in 2008 and seems to have been absorbed by its parent company, which itself is owned by Amazon. At the time, Box Office Mojo said it would remain a stand alone company.
Also read: NeonGrid Is Building IMDb for YouTube Stars
Box Office Mojo is a critical tool for movie industry executives in Hollywood who look to the site for real-time box office results and historical and comparative data. It was founded in 1999 by Brandon Gray as a three-person company headquartered in Burbank.
IMDb has a vast collection of data on films, but is lacking in detailed data on box office metrics. It is unknown how IMDB will incorporate the Box Office Mojo data into its system. The layout for Box Office Mojo is set up solely for an in-depth look at box office metrics, while IMDb fills many roles, highlighting trailers, movie stills, cast lists and fan commentary.
IMDb has not yet responded to TheWrap's request for comment and there has been no official word or message posted from IMDB or Box Office Mojo's official Twitter accounts.