Pretty interesting list
A country by country breakdown of the 350+ players from nations outside Tier 1 currently playing for clubs in one of the 5 fully professional leagues in Europe (Premiership, Championship, Top 14, Pro D2 and Pro12).
Note: This list needs to be considered with the following in mind. This is just a list of players who were either (a) born in the country or (b) represented the country at any level and (c) made their senior first team debut at club level for any club. Players who have represented another nation, like Tim Visser (Dutchman who plays for Scotland), are not included.