How well did Temasek manage our reserves?

Attached is an article on Singapore and Temasek Holdings in the Fortune magazine of 20 March 2006, "Singapore Stumbles". I also refer to Temasek's letter to the Straits Times, Feb 7, 2006, "Temasek's 30-year returns a robust 18%". When I saw this statement pasted in the YPAP forum, I was dumbfounded. 18% in 30 years is considered robust? I put in fixed deposit for 30 years with a 2% interest will give me 60% return with no risk. And if the interest rate averages at 3%, I will get 90% return. What is 18% to crow about and managed by a team of experts and incurring all the risk of losing a bundle if the investment decisions went wrong? Today it was reported that GIC opened its book to detail its investments and LKY said GIC 'has earned an average of 8.2% a year in Singapore dollar terms since 1981.' Now this is more like it. How did Fortune get that 18% figure? I will be deeply disappointed if that is the case.