https://phys.org/news/2018-07-quality-science.html

Each year, 1.7 million scientific articles are published (as of 2017), which are listed in the reputable Web Of Science database. Web Of Science lists only recognized scientific journals. The journals of the publishing company OMICS, an example of a predatory publisher, are currently not listed in Web Of Science. Compared to the number of articles listed in Web Of Science, the total number of articles distributed by OMICS is less than 0.9% (as of 2017). Apparently, this is rather a marginal phenomenon.

In the years 2007-2017, the Max Planck Society has produced more than 120,000 scientific articles with the participation of Max Planck authors. Amongst these articles, only nine articles appeared in OMICS magazines. This is a negligible share of 0.01% of MPG articles. At least three of these publications are transfers, i.e. at the time of publication the journal was produced under the umbrella of an established scientific publisher and only later purchased by OMICS. This means that not all articles distributed under the umbrella of a dubious publishing house are automatically spurious.