In the land registry stats released in June 2008 the average price for all properties was:
May 2007 : Â£179,978
May 2008 : Â£183,266
While the latest set of stats show:
May 2008 : Â£181,435
May 2009 : Â£152,497
So between doing the stats last year and this year the average price for May 2008 fell by Â£1,831 (about 1%). I assume this is down to things that hadn't been completed when the stats were first produced. But it suggests that the annual drop of 15.9% just published could easily reach 16.9% once all the data has come in.
Also the drop between 2008 and 2009 is touted as a 15.9% drop. If the prices had gone the otherway then it would have been a 18.9% rise.