YouTube had the biggest gains in number of searches on Google search last year, and Reddit had the biggest drop, according to recent research from Searchmetrics.

The report was based on the SEO visibility scores—a combination of organic search volume and rank position of pages—for major websites.

The researchers compared each site's level at the end of 2017 with its position at the start of the year. Adult websites and illegitimate streaming sites were excluded from the analysis.

YouTube had the largest absolute gain in SEO visibility in 2017. Encyclopedia and dictionary properties also had large SEO visibility gains last year, including the websites of Merriam-Webster and Encyclopedia Britannica.