While many western and central European countries have long ago reached put equal or greater portions of their citizens on Facebook as compared to the United States, Germany has lagged behind, clinging to its native social networks. But our latest edition of the Facebook Global Monitor suggests that the German trend is reversing, with over 10 percent growth in April 2010, up from about seven percent in March.

Growth for Germany has risen throughout the year, allowing the country to finally crack 10 percent penetration; if it accelerates through the summer, it’s conceivable that Germany will cross 20 percent before Christmas. However, there’s still the possibility that its growth will take a sudden dip down the line — just as we’re seeing this month with France, which fell from a high of 1.2 new monthly active users in March.

Following Germany is Turkey, which brings up an interesting point: it could be that Germany’s large Turkish population is helping drive growth on Facebook. But Turkey’s growth as a percentage of its population was actually pretty slim in April; the country simply has a much larger population than its entirely European neighbors. That’s also the case this month with the United Kingdom.

Spain and Italy are both keeping up their steady growth rates, which date back several months, while Sweden showed up out of nowhere with almost 10 percent growth for April — its overall penetration is already rather high.

One thing we’re not seeing nearly as much of for April as in March and February is growth in eastern European countries like Romania — which just made it on — and Bulgaria. We’ll likely see those countries come up from time to time, but with smaller populations and fewer people on the internet than the richer countries to the west, they’ll struggle to put large numbers of people on Facebook.

It’s also worth looking into our post from two days ago about recent fluctuations in Facebook’s numbers. Following an unexplained dip in February, Facebook appeared to regain its footing in March, along with the other major social networks. Our data is sourced from Facebook’s advertising tool, which runs a few weeks behind, so there could be some residual effects from either month in the traffic stats.

The full Facebook Global Monitor, May 2010 edition, is available through Inside Facebook Gold, our data and analysis membership which also includes analysis on developments, risks and opportunities in the Facebook business ecosystem