end of 2010 property prices, page-99

Dalek may I ask a question to save me reading through the entire thread?
Using RP Data/Rismark hedonic index is is good as they're the benchmark, but how will you determine the % level of increases/falls at the end of the year?
Is it over the entire year (ie so that I need to factor in the reported 5% increase from January to May) or is it fall % from peak (assuming May is the peak as June displayed the first fall)?
Many thanks