Upworthy doesn’t always get a lot of love in some of the more high-minded parts of the Internet, but there’s plenty to learn from their success building the fastest-growing news site on the web. In an end-of-year review, Upworthy has released some data on its most shared stories. The blog post that sums it up includes an engaging interactive that breaks down posts by popularity and categories like body image, income inequality, and gay marriage. Some of the big analyses:

— We saw that tens of millions of Internet citizens are deeply concerned about the way women are treated and the way they (and their bodies) are portrayed in the media. Posts about women’s body image, about how the media distorts societal ideas about beauty, and about equalizing the opportunities available to girls and boys were all hugely popular. In all, viewers shared, tweeted, liked, commented on, or pinned the 22 posts on these topics more than 14.5 million times.

— We also saw that, contrary to popular wisdom about what goes viral, neither “difficult” subjects nor fact-filled presentations scare people off. Nearly 20% of the people who watched a deep dive into American health care policy thought it was worth passing along to their friends. A powerful historical video of a teacher giving her young students a firsthand lesson in bigotry was viewed more than 3 million times. And four of the posts in the top 100 were about the important (but thoroughly unsexy) topic of income inequality.