Keeping track of how many people visit websites is something that should have been hashed out long ago. Yet for years keeping tabs on such matters has produced results that can vary wildly for each site depending on who is doing the measuring.

Nielsen Online and comScore,  for example, are two companies that rely on panels of people to determine the popularity of a website and are often criticized for under-counting visitors.  Many critics claim that panels barely account for people’s Internet habits at work since often companies do not allow outside software to be installed on work computers. (Nielsen and comScore require panelists to install software on their computers.)

This has been a problem for newspapers websites since many read the news during the work day hours.

ComScore, though, had announced a new methodology that relies on panels as well as  counting direct hits from a website’s server.   Eighteen of the top 20 newspaper entities are now on board with the new methodology. Here are the top 10 ranked by uniques for May.