Expatriation has been increasing each year by roughly 30% since 2010, which featured abnormally high expatriation rates, most likely attributable to the economic turndown of the Great Recession which began in the United States as a result of the sub-prime mortgage crisis. American citizenship is often sought after for the economic opportunity that comes along with the passport, as the ability to work and do business in the country is heavily restricted or regulated, and with the value of that investment or opportunity in question, it is unsurprising that the number of investors in the system, that is, new citizens, would fluctuate. It seems appropriate to call naturalization an investment because of the nature of the process, which is long, complicated, and often quite expensive similar to a long-position that will cost more at purchasing time but promises high returns after reaching maturity.
The peak, or more appropriately, valley of the global recession occurred in 2009 when the global GDP contracted causing a decline in the median familty income of about five percent.