The dollar's share of world reserves has dropped.

THE NUMBERS: Dollars, as share of world's allocated foreign reserves:

2000: 71%
2005: 67%
2009: 61%

WHAT THEY MEAN:

The dollar is used to price gold at the London Bullion Market Association and cocoa futures at the New York Board of Trade. Vendors prefer it to the sucre and the kip as they settle bills for hot soup in La Paz and T-shirts in Vientiane. Accountants at the People's Bank of China in Beijing and the Central Bank of the Republic of China in Taipei use it as their main currency reserve. And foreign exchange traders use it in 86 percent of the world's $4 trillion in daily currency turnover. Having taken over the reserve-currency role from the pound in 1939, the dollar has held these mighty roles for a life-time.

The next life, though? The dollar's reserve role peaked at 84.5 percent of all reserves in 1973 (for aficionados, this was just before the "Nixon shock" and the return of fluctuating currency rates), retreated to about 65 percent in the gloomy 1970s and 1980s, and rebounded again above 70 percent by the year 2000. And since then it has dropped fast.

As of late 2009, world reserves were about $7.5 trillion, or about 10 percent of world GDP. Of the $4.34 trillion in "allocated" holdings -- i.e. the reserves held by 140 countries which make their divisions by currency public -- the biggest pool is China's $2.4 trillion, followed by Japan's $1.0 trillion, Russia's $440 billion and Taiwan's $350 billion. Dollars accounted for $2.73 trillion of this allocated total, euros $1.23 trillion, sterling $192 billion and yen $143 billion. ("Unallocated" reserve holdings are those in countries not choosing to report to the IMF. The IMF is chastely quiet about their identity, but countries in question appear from outside evidence to be mostly oil-producers; their currency holdings are probably similar to those of the reporting countries.)  With a declining dollar value and economic troubles in the United States, the dollar's share of allocated reserves fell to 67 percent in 2005 and 61 percent by late 2009. Holdings of UK pounds and euros are rising as the dollar retrenches; the shift presumably reflects a combination of lower dollar values with voluntary choices to invest in other currencies.

FURTHER READING: 

Explainer -- How much is $7.5 trillion in total reserves? Measured against four different yardsticks, $7.5 trillion is about --

• Half of the United States' $14.4 trillion GDP; 
  
• Ten times last year's roughly $700 billion in total stimulus program spending around the world; 
  
• A bit more than a tenth of the world's $73 trillion GDP;
  
• A bit less than a tenth of America's roughly $80 trillion in total wealth.

World asset wealth, or the combined value of all world stocks, real estate, bonds, oil reserves, cash, machinery, old-growth forests and so on -- is rather difficult to calculate, but the UN estimated this at $125 trillion for 2000, when total foreign reserves were only $2 trillion. Assuming reserves grew lots faster than wealth in the last decade, the world ratio of reserves to assets might be around 3 percent.

Some data -

The U.S. Treasury Department (April 2009) reports on foreign currency practices:http://www.treas.gov/press/releases/tg90.htm

IMF's COFER tracks reserve holdings and shares by currency, 1995-2009:http://www.imf.org/external/np/sta/cofer/eng/index.htm
Meanwhile, electronic trading transmits about $4 trillion worldwide each day, probably a bit more than all the coins, bills and other forms of hard cash in circulation. The Bank for International Settlements, a central-banker conclave in Basel, studies currency circulation every three years. The last study dates to April 2007, and found about 86 percent of all currency trades involving dollars. The next should be out by the end of this year:http://www.bis.org/publ/rpfxf07t.htm

Two things that are traded in dollars:

Cocoa, from the International Cocoa Organization: http://www.icco.org/about/shipping.aspx
Gold, from the London Bullion Market Association:
http://www.lbma.org.uk/

Two busy dollar-collectors:

Governor Zhou of the People's Bank of China speculates, so to speak, on a new international reserve system: http://www.pbc.gov.cn/english/detail.asp?col=6500&id=178

His counterparts in Taipei stay closer to home affairs: http://www.cbc.gov.tw/mp2.html

And two businesses using dollars: