Note that 155 is the grand total over the entire duration of the operation. The tally (given in your linked video) is:

* 70 yesterday in Sweden

* 5 yesterday in Spain (related to Swedish investigations)

* 80 earlier, candidly

I believe 70 is the figure that should be compared with the 800 total [1].

> A series of large-scale law enforcement actions were executed over the past days across 16 countries resulting in more than 700 house searches, more than 800 arrests [...]

1: https://www.europol.europa.eu/newsroom/news/800-criminals-ar...

Which amounts to almost 20% of those arrested. Maybe it's partly due to Sweden historically having strong computer literacy. Only time will tell.