According to this article on Media Village, digital ad spending has increased substantially in recent years, including+29% for the first three quarters of 2015 year-over-year (YOY). In particular, there has been a remarkable increase in ad spend for social and digital video. This trend coincides with a decrease in spending for traditional television ads.
While quantifying ROI is difficult in the midst of ad-blockers and fraud, it’s clear that the trend towards more engaging ads is substantial. Part of that could be because, while still difficult to calculate, ROI is more traceable with social than with other traditional media.