Which of the following is correct?
1. Worldwide GDP per head has grown steadily since the year 1000 A.D.
2. Economic growth since 1800 has been higher than at any other time.
3. Europe has always been relatively wealthy compared to Africa.
4. Life expectancy is little different now than what it was in 1500.
Answer: 2. Economic growth since 1800 has been higher than at any other time.