According to new data from comScore, Facebook had 27.9% of all online display-ad impressions last year, up from 21% the previous year.

According to the firm, Yahoo was in second place at 11% (up from 10.9% the year before), leaving Microsoft, Google and AOL each with less than 5%.

That would make three years in a row that Facebook led the charge. And why not? Who has better targeting, and where are users spending more time?

Facebook, of course, is expected to file for its huge IPO this week, and this news should only help. Add that to the various ways Facebook is expanding its advertising offerings.

This month, for one, ads came to the Facebook news feed.

The company is incentivizing advertisers to stay with Facebook with a 45% reduction in CPCs, according to TBG Digital’s recent Global Facebook Advertising Report Q4.

Recently, we’ve seen reports of Facebook cold emailing businesses, offering phone consultation on Facebook advertising.

Facebook is expected to start offering mobile ads soon, and there’s always that possibility that the company will eventually launch an AdSense like network for publishers. That one’s pure speculation, but come on. How could they not?