The number of reported photos, videos and other materials related to online child sexual abuse grew by more than 50 percent last year. Nearly 70 million images and videos were reported to the National Center for Missing and Exploited Children, a federally designated clearinghouse for the imagery that works with law enforcement agencies. Over 41 million videos were reported; the number five years ago was under 350,000. The center identified ... the companies that had detected the imagery, the first time detailed company information had been released. The companies flagged many of the same images and videos multiple times as they were shared among users. Facebook reported nearly 60 million photos and videos, more than 85 percent of the total. About half of the content was not necessarily illegal, according to the company, and was reported to help law enforcement with investigations. Instagram, owned by Facebook, was responsible for an additional 1.7 million photos and videos. Snapchat, Twitter and other social media companies also submitted reports of imagery. So did ... Google and Microsoft. Apple, Dropbox and the chat platform Discord also detected the illegal content. In all, 164 companies submitted reports. Some companies that made a small number of reports ended up finding a large volume of imagery. Dropbox, for instance, made roughly 5,000 reports last year but found over 250,000 photos and videos.