This is easy and it's happening more and more frequently. Today's games are much more likely to have female non-victim playable characters. But if that's going to be a gauge for any kind of improvement over time, then you have to establish a reference date. For example:
2003 -- Year Zero -- X number of games and Y% of games on the market have the option to play female lead characters.
2004 -- Year One -- X number...
But then you can't go back and say, ".01% of all video games made between 1982 and 2014 have had the option of playing a female lead character." That would be disingenuous. That would be holding today's developers and writers accountable for actions taken by other developers while today's developers were in primary school. At some point, you have to have the integrity to say, "The old generational thought is dying out. The new generational thought is taking hold. It just takes time from here."
And still, you can't force game designers to choose to make a character female any more than you can force a novelist. Part of game creation is following a creative vision. Yes, studios can make such changes. Yes, we can HOPE that newer game designers have the same gender-based sentiments as we, but since it is still an artistic endeavor, they should have the freedom to create the games they wish to create... with the audience deciding if it's a game they want to buy.
"Assuming that art is ultimately a cultural product, what does that say about the gaming industry's attitudes toward women? How do they compare to other creative industries? (Movies, TV, etc.)"
It says a couple things-- neither are too surprising. Young girls are taught to want to be rescued. Young men are taught to want to rescue. After the rescue transaction, adult-oriented fiction asserts that there's an expectation of physical intimacy. That's the fantasy story that told day-in and day-out. Sometimes the story is reversed. Sometimes it includes the same gender. It says nothing about women but quite a bit about our **historical** fantasies.
Today's stories are different. Resident Evil, Salt, Twilight, Harry Potter-- Female competence and heroism is a celebrated expectation and is becoming more and more mainstream-- not because peoples' tastes are being forcibly changed, but because kids grew up with the expectation that boys and girls can both be whomever they wish.
It's generational. The old and their ideas will die off. The new and their ideas will replace them. So just make sure not to hold the new accountable for the actions of the old. Hell... don't even lump them into the same categories.