This exercise is based on the following table, which lists interest rates on long-term investments (based on 10-year government bonds) in several countries in 2014.

Country	U.S.	Japan	Germany	Australia	Brazil
Yield	2.5%	0.5%	1.0%	3.5%	4.2%

Assuming that you invest $6,000 in the United States, how long (to the nearest year) must you wait before your investment is worth $16,000 if the interest is compounded annually? ___ yr