eMarketer has just released their latest rankings of the top 5 ad markets in the world in 2015, showing that ad spend globally will hit $592.43 billion in 2015. That represents a 6 percent increase over 2014. The United States is still on top as far as ad dollars go, but China has ramped up considerably at the #2 spot.

eMarketer’s data breaks out what the total digital picture looks like and what part mobile plays in that as well. Worldwide, digital ad spending is expected to be $170.50 billion and of that, $64.25 billion is projected to be specific to mobile.

Just today, eMarketer released another study that by 2016, the number of smartphone users will surpass 2 billion, a considerable portion of the planet. As mobile continues it’s reach globally, becoming the almost-everyman’s platform, the ad spend is beginning to move in-step.

“Mobile advertising is the key driver of growth around the world, and advertisers will spend $64.25 billion worldwide on mobile in 2015, an increase of nearly 60 percent over 2014. That figure will reach $158.55 billion by 2018, when mobile ads will account for 22.3 percent of all advertising spending worldwide,” says eMarketer.