Each month the NPD Group releases data about sales in the U.S. video game industry, including a closely watched list of the top 10 selling software titles. Unfortunately for market data mavens, the top 10 provides only a tiny window into the larger market.

When dozens of games are released each month across no fewer than six console and handheld platforms, there simply aren't enough data points to see how games are selling on each platform.

However, in coordination with the NPD Group, Gamasutra has exclusive data on the top 5 titles for each of the current-generation consoles.

While these are simply additional small windows on the market and not the type of broad view that a top 100 or even top 20 might provide, they do help illuminate what kind of software is selling on which platforms.

PlayStation 3

Here are the top five selling titles for the year on the PlayStation 3, through the end of August 2008.

Note that this ranking does not include collector's editions and software bundled with hardware. Therefore, the Metal Gear Solid 4 ranking does not count the Collector's Edition, nor does it count copies bundled with 80GB PlayStation 3 units.

Seeing Grand Theft Auto IV and Metal Gear Solid 4 at the top of the listing is not a huge surprise. The former moved 1.4 million copies (including the Collector's Edition) in its first two months, and Kojima's latest opus moved around a million in its first month when hardware bundled copies were counted.

These two games were heavily promoted and were considered system sellers, although only MGS4 can probably claim that moniker with any real certainty.

Meanwhile, we now know that the PS3 version of Call of Duty 4 had enough sales after Christmas 2007 to put it somewhere north of 600,000 copies for this year. (The NPD Group did not release unit sales data to us for these titles, so rough estimates will have to suffice.)

The staying power of Call of Duty 4 is simply amazing, and Activision will be fortunate to score again this year with Call of Duty 5.

The last entry in the list, Gran Turismo 5: Prologue is a bit of a surprise, at least to us. We had thought it probable that Devil May Cry 4 would have beaten out GT5P, but these figures suggest otherwise.

Depending on how well GT5P has sold through the PlayStation Store, it is possible that it has sold more copies (via retail and download combined) than the PS3 version of Madden.