Greece is part of the Schengen area, which includes Sweden, so whatever xenophobes think, that's their problem. The basic classification is EU vs non-EU, and one can split the non-EU, non-asylum immigrants into categories, each to its own taste.

A few years back I dug a bit into the Dutch numbers on African illegal immigrants - but I found there isn't anything solid on non-asylum immigrants in regard to official figures, just estimates based on the numbers of police arrests, when police by coincidence discover someone has no legal status. It is not actively measured by policy, rarely researched and exceedingly difficult. Other means to attempt tallying the size of this group can be thought of (e.g. hospitalization), but these too would also form a proxy at best.

But what else is to be expected with a harsh government policy that actively pursues sending illegal immigrants straight across the borders and is blind for the very possible bureaucratic nightmare when people get stuck between nations and become de facto stateless? The upshot is that non-asylum immigrants (or those that applied and were not recognized) in the Netherlands actively avoid the means of government bookkeepings and drop out of the system and into darker circuits, with all the consequences that entails. Yet even stuck in these conditions, the people I interviewed confessed they were happier here than back home.