Hong Kong Dollar vs. Chinese Yuan

The Hong Kong dollar has been pegged to the United States dollar since 1983 at HK$7.80 per U.S. dollar through a currency board system (see graph above, left scale). China has also successfuly stabilized the value of the Chinese yuan over the last ten years, not through a currency board, but with the same results as a currency board (see graph above). China has now let its currency depreciate by about 6% over the last year, partly under pressure from the U.S.

Q: Why do people complain about "currency manipulation" of the Chinese yuan, and not about "currency manipulation" of the Hong Kong dollar, when both countries have attempted to maintain stable currencies vs. the USD, just through slightly different approaches? Perhaps Treasury Secretary Paulson should stop in Hong Kong after his trip to China, to pressure Hong Kong to end its currency board, and 25-year history of a stable ex-rate vs. the USD?

See the results here of a Google News search for "China currency manipulation" that returns 256 examples of that phrase in recent news reports. See the results here for a Google news search of the phrase "Hong Kong's currency manipulation" that returns O examples of those words. There are about a dozen countries around the world using currency boards, with the express intention of a stable currency and stable ex-rate vs. some stable currency like the pound (Falkland Islands), euro (Bosnia, Lithuania) or dollar (Cayman Islands, Bermuda, Hong Kong).

Perhaps China should move to a currency board? Results would be the same, but the charges of "currency manipulation" would stop.