Many readers of this blog already may have come across darts-ip's February 2018 study "NPE Litigation in the European Union: Facts and Figures," but if not here's a link; it's an interesting study. From the executive summary:
This report provides a factual overview of Non-Practicing Entity (NPE) related litigation and patent enforcement activities across the European Union (EU), including opposition actions filed before the European Patent Office (EPO). The findings are based on Dartsip’s database of IP case-law. With information on more than 3 million cases worldwide, this database constitutes the largest IP case-law database in the world. The reported statistics are calculated from the set of all patent-related actions contained in the database which have had their first registered procedural event in an EU court or IP office between the 1st of January 2007 and the 31st of December 2016. The majority of cases are infringement, invalidity and opposition actions.
The overview reveals a marked year-on-year upward trend in the number of actions involving NPEs in the EU, with a dramatic increase in the last five years, primarily concerning Information and Communication Technologies. . . .
The report finds that, in the EU, NPEs prefer litigating in Germany. During the 2007-2017 period, about one in every five infringement actions in Germany was NPE initiated.
The report states that NPEs' preference for Germany may stem from, among other considerations, the bifurcated nature of Germany infringement litigation, "with injunctions often being granted prior to completion of the invalidity action." For fairly extension discussion of the report on the IPKat Blog, see here and here, and on the IAM Blog, see here.
On a related note, in February the China IPR Blog reported on a report on an article on NPEs in China authored by King & Wood Mallesons, which report however appears to be in Chinese. According to these sources, however, NPE activity in China at present appears to be at a minimum, though there are a variety of NPE-type business models operating there.