Digital ad revenues in the U.S. surpassed $100 billion for the first time last year, according to an annual Interactive Advertising Bureau report prepared by PricewaterhouseCoopers.

Digital ad spends accounted for $107.5 billion in the U.S. last year, according to the IAB report, a 22 percent increase from 2017’s $88.3 billion.

Digital ad revenues gained 18.1 percent in 2018’s fourth quarter alone (or $4.8 billion), from $26.6 billion in Q3 to $31.4 billion for the end of the year. Second-half 2018 revenues totaled $57.9 billion, an increase of nearly $10 billion from 2017’s second-half.

Desktop vs. mobile Internet advertising revenue for full-year 2018 (in billions).

Desktop vs. mobile Internet advertising revenue for full-year 2018 (in billions).

Mobile was responsible for driving a significant amount of those annual gains, surging 40 percent from 2017’s $50.1 billion to $69.9 billion last year. Advertising delivered on mobile devices now accounts for more than 65 percent of total Internet advertising revenues, according to the IAB report.

Meanwhile, desktop’s share of the Internet ad revenue pie continued to shrink last year, to $37.6 billion in 2018, compared to $38.2 billion in 2017. While now accounting for less than 35 percent of total Internet ad revenues, desktop comprised virtually 100 percent of online ad sales a decade ago, according to IAB figures.

The report also revealed that ad revenues from digital video totaled $16.3 billion in 2018, up 37 percent from 2017 to now account for more than 15 percent of total digital revenues.

Digital ad spends should continue to outperform this year. A recent report by digital market research company eMarketer predicted total digital ad revenues will gain 19.1 percent in 2019 to a historic $129.34 billion.

Digital ad growth would remain elusive for print publishers, however, gaining just 2.3 percent for newspapers and only 2.1 percent for magazines, according to the eMarketer report.

The IAB’s “Internet Advertising Revenue Report” utilizes information gathered by PwC from companies selling advertising on the Internet as well as publicly available corporate data.