Here is an interesting chart showing the yield on long government bonds of US and UK. In the 1970s and 80s, British bonds yielded over 12% while US bonds over 7% and 10% respectively. Since then the yields have fallen dramatically for both country bonds. At the end of last year 20 year government bonds yields stood at 2.5% for the USA, 2.7% for the UK, 2.0% for Germany, and 1.0% for Switzerland.

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Related ETFs:

iShares Lehman 7-10 Year Treasury Bond Fund (IEF)
iShares Lehman 10-20 Year Treasury Bond Fund (TLH)
SPDR Lehman Long Term Treasury ETF (TLO)
SPDR Lehman Intermediate Term Treasury ETF (ITE)
iShares Lehman TIPS Bond Fund (TIP)
Vanguard Long-Term Government Bond Index Fund (VGLT)

Source: Credit Suisse Global Investment Yearbook 2013, Credit Suisse