'As much as' 85% of Facebook video is watched without sound

"Facebook might be hosting upwards of 8 billion views per day on its platform, but a wide majority of that viewership is happening in silence.
As much as 85 percent of video views happen with the sound off, according to multiple publishers. Take, for instance, feel-good site LittleThings, which is averaging 150 million monthly views on Facebook so far this year. Eighty-five percent of its viewership is occurring without users turning the sound on. Similarly, millennial news site Mic, which is also averaging 150 million monthly Facebook views, said 85 percent of its 30-second views are without sound. PopSugar said its silent video views range between 50 and 80 percent.
The news shouldn’t come as much of a surprise, as Facebook has built a video ecosystem that does not require users to turn the volume up — and publishers have been more than happy to play ball. Most users’ news feeds are now inundated with short videos that feature text or captions narrating what’s being shown on screen. While most of these videos feature narration or some form of background music, the intent is to make it easy for people to consume the information presented in the videos without needing to turn the sound on."
Source:  Digiday, 17th May 2016
Note - So keep it visual, and use subtitles!