According to this article, only 28.4% of the top-100 grossing films of 2012 included speaking roles for women. (Hat tip to @lindseybieda for the heads up!)
According to Wolfram Alpha (I'm happy to use a better or more complete source if one is available... Also I don't have a ton of time to put into this research at the moment...), the top 10 are:
- The Avengers (Scarlett Johansson, Gwyneth Paltrow)
- The Dark Knight Rises (Anne Hathaway, Marion Cotillard)
- The Hunger Games (Jennifer Lawrence, Elizabeth Banks)
- Skyfall (Dame Judy Dench