Depends on how aggressively pricing was/is.
Those numbers sometimes are hard to verify as:
1) homes ahve to be in one of the many MLS systems used in the US.
2) homes may get unlisted, expired, failed contracts or relisted with a new broker - and the data is more or less lost without doing a real analysis
3) many bnak properties, forclosures etc won't be reflected and can also play into an areas data
But use 4- 9 months.
check with a several brokers in your immediate area or the area you are interested in for good data.