Digital advertising saw the most growth, finishing the month of December up 34% compared with December of 2014. Digital advertising was up 26% year-over-year, with social media sites making up the most growth at 71%. TV ad spending declined slightly in December, down 3% compared with the previous December, and was flat year-over-year. This was mainly due to networks continuing to suffer through declining ratings.
Source: TV ad spending was flat in 2015, as digital ads soared – MarketWatch