Help a Mom: When do kids start reading 'The Hunger Games'

I'm the mom today asking this question: How old were your kids when they read The Hunger Games series? 

My third grade daughter, an advanced reader, has been asking me to read the hugely popular trilogy. Her friend of the same age has read all three books and seen the two movies released so far. I've told her no. I've read the books and, while I know she'd enjoy the story line, I feel like some of the content is a little too dark. 

Of course, I didn't have a problem with her reading the entire Harry Potter series, which she's devoured more than once. That certainly has plenty of dark themes. But The Hunger Games strikes me as a different series all together with lots of violence and romantic relationships.

I won't bend in my decision to have her hold off for a couple of years before she reads the series, but I'd love to find out when your kids read the books (and what other books they really enjoy).