How do you find out if a product is selling well?

You know how there's websites that post tv ratings to let you know if a show is doing well? I was wondering if there was any kind of website like that but instead of with tv shows, they tell you if products (such as dolls/toys/games etc) are selling good? Maybe like a financial website or something.

If you know of any website like this could you please give me a link? Thank you!

If you know how to use search engines properly you can find just about anything. See the links for a sample of what you might find online.

Source(s):

ec.europa.eu/enterprise/sectors/toy...
www.statisticbrain.com/total-harry-...