Search remains the strongest media for mobile advertising, but social will take the lead beginning in 2019, according to data released Monday. The two channels will account for 81% of the incremental mobile ad dollars spent between 2017 and 2022.

Advertisers spent $20.6 billion on mobile search in 2017, or 44% of the market, according to Forrester’s research. The study — Forrester Analytics: Mobile Advertising Forecast from 2017 to 2022 (US) — highlights growth for mobile through 2022 for a variety of channels, from search and social to video and display.

Despite mobile search’s slow compounded annual growth rate of 12.5% from 2017 through 2022, the channel will still account for 36% of marketing and advertising dollars spent on mobile ads during those years. Forrester estimates that growth, in part, will come from the number of mobile phone users, which is estimated to rise at a 3.5% CAGR from 204.4 million in 2017 to 242.8 million in 2022.

Another possible reason for the increase is that mobile users worldwide are reinstalling apps at a higher rate — about 42% for reinstalls and 58% for initial installs, according to Tune data. The catalyst is paid-search ads in app stores such as Apple, according to the data.  

The share of U.S. online adults who conduct a search at least weekly on a mobile phone grew from 38% in 2013 to 57% in 2017, while those who search weekly on a PC came in at about 80%.

Forrester analysts, which cite data from the advertising agency Merkle, expects mobile search prices to rise, given they are about 67% below PC search ad prices.

Mobile ad spending in the U.S. will see a 14.7% CAGR from 2017 through 2022, compared with 3.9% for PC during the same period, but video consumption rates will push up growth rates for mobile display. Video consumption will see a CAGR of 16.7% from 2017 to 2022.

Forrester estimates the industry will settle on a six-second video ad, but I think that number will be more around eight to 10 seconds. For Snapchat, 60% of its ads are between eight and 10 seconds and the remainder are 5 to 7 seconds, according to Forrester’s report, citing MediaRadar.