The I.M.F. has a complex definition of “advanced,” but a common thread is that all the nations have a per-capita income of at least around $15,000. Since Poland completed the transition from Communism to democracy in 1991, its economy has been growing at an average annual rate of 4 percent and, remarkably, has not suffered a single year of negative growth. In those 25 years, Poland’s average income has risen to near $13,000, from $2,300, and it is now on pace to pass the $15,000 mark by the turn of this decade.