How Effective Is Advertising on Steem?

In advertising, CPM, or Cost Per Mille, is a metric that determines the money needed to advertise to a thousand people. For Twitter, the average CPM is $3.5 while for Google AdSense the average cost is around$1.5. But how much is it for the Steem promoted section?

As a business owner, I wonder what a good estimate would be for the relationship between the amount of Steem spent to promote an article and the number of views that it gets. Would it be better to power up one's account and upvote themselves or spend it on promoting a post? And of course, what is the CPM in USD/STEEM?