Facebook has nearly 20 million users in major African markets Nigeria and Kenya, statistics released by the social network showed on Thursday, with the majority using mobile devices to access their profiles.

Facebook opened its first African office in Johannesburg in June as the continent’s growing population and relatively low levels of internet access present a large untapped market for the social network to earn advertising revenue.

The numbers, the first Facebook has published for Nigeria, Africa’s most populous nation and Kenya, East Africa’s most developed, show the two nations as important entry points on a continent of nearly one billion people.

Nigeria had 15 million monthly active users as of June 30 this year, all of them using mobiles to like, share and upload content on the social network. In Kenya, 95 percent of the 4.5 million monthly active users did so via mobiles.

“Mobile is not a trend; it’s the fastest adoption of disruptive technology in history of communication,” said Nunu Ntshingila, Facebook’s head of Africa, in a statement. Read more