Colin Gleadell has done a little arithmetic on Sotheby’s site to come up with a total figure for worldwide auction sales in 2011:

The auction houses will not produce their annual sales reports until next year, but figures on Sotheby’s website indicate that there has been a 12.2 per cent rise in its worldwide auction sales to $4.9 billion. However, while sales up to the end of July were generally meeting and sometimes exceeding expectations, since September, in Europe and the UK, they have consistently fallen below their estimates. Although there are exceptions, the trend suggests that the eurozone crisis has taken its toll. […] , it is uncertain whether Sotheby’s will reach the record $6.2 billion for a year, achieved in 2007, but it will be close.

Art Sales: Review of 2011 (Telegraph)