Please answer a question about the following article about YouTube:

In 2014 YouTube said that 300 hours of new videos were uploaded to the site every minute, three times more than one year earlier and that around three quarters of the material comes from outside the U.S. The site has 800 million unique users a month. It is estimated that in 2007 YouTube consumed as much bandwidth as the entire Internet in 2000. According to third-party web analytics providers, Alexa and SimilarWeb, YouTube is the third most visited website in the world, as of June 2015; SimilarWeb also lists YouTube as the top TV and video website globally, attracting more than 15 billion visitors per month.

How many unique visitors a month were tracked as of 2014?
800 million