Does Taylor Swift dye her hair?

I mean, I know she's a natural blonde. You can tell that much. But it seems to have been getting darker. Her hair was really light blonde when she was like 16 or 17 and now it's like ash blonde. But blonde hair naturally gets darker with age, so I wasn't sure. If you look through pictures of her through time, you can kinda see it growing out darker. And there's the whole issue of lighting, and seasons, and everything. I just want to know for sure.