Digital advertising in the U.S. reached $59.6 billion in 2015, an all-time high, according to the Interactive Advertising Bureau (IAB). This represents a 20-percent uptick from 2014’s then record-breaking $49.5 billion internet advertising performance and the sixth year in a row the segment has registered double-digit growth.

The IAB’s Internet Advertising Revenue Report, prepared by PricewaterhouseCoopers US (PwC US), also found that fourth quarter 2015’s $17.5 billion was up 23 percent from fourth quarter 2014’s $14.2 billion, and 18 percent above third quarter 2015’s $14.7 billion.

“Internet advertising was a disruptive innovation when the industry was formed,” says David Silverman, partner at PwC US. “Twenty years later we still see double-digit growth rates, including 20 percent in 2015. Three key disruptive trends—mobile, social and programmatic—continue to fuel this exceptional rate of growth.”

Mobile represents a significant share of the pie, accounting for $20.7 billion in spending in 2015, a 66-percent increase over 2014’s figure. Non-mobile search reached $20.5 billion, up eight percent from 2014, while non-mobile display-related advertising’s total of $13.9 billion grew three percent. Social media advertising’s $10.9 billion in 2015 represented a 55-percent increase over 2014, and non-mobile digital video also registered significant growth last year, rising 30 percent to $4.2 billion.

Retail holds on as the largest category of internet ad spending, accounting for 22 percent of the total in 2015. Automotive and financial services followed, each accounting for 13 percent.

“There is no question that interactive screens are attracting consumers and the advertisers that want to reach them where they live—increasingly on mobile devices,” says Sherrill Mane, senior vice president of research, analytics and measurement at IAB.