NEW YORK (AP) — Nearly three-quarters of Facebook's advertising revenue now comes from mobile ads, as many more users access the social network on smartphones and other handheld gadgets. Facebook, which bought the popular photo-sharing app Instagram and the messaging service WhatsApp, has been coming out with its own stand-alone mobile apps to capture more of the time people spend on phones. Besides its Messenger app, though, Facebook home-grown efforts have had limited success.