In a down month for video games, Microsoft’s Xbox 360 continued to buck the trend in May, according to new data out this afternoon.

Microsoft sold 270,000 Xbox 360s in the U.S. in May, up 39 percent over the same month last year, according to data compiled by the NPD Group market research firm. The Microsoft console has now held the No. 1 slot, ahead of Sony’s PlayStation 3 and Nintendo’s Wii, for 11 out of the past 12 months in the country.

NPD noted that the Xbox 360 has “realized nearly a year and a half of month-over-month unit sales increases.” Microsoft’s Kinect motion sensor has breathed new life into the Xbox 360, resulting in higher sales at a point in the console life cycle that typically brings declines.

Even with Microsoft’s progress, the Wii remains the overall leader in cumulative console sales this hardware generation in the U.S. and worldwide, thanks to its huge sales volumes in the initial years following its release. Nintendo last week unveiled plans for a new console, the Wii U, featuring a motion-sensitive controller with an embedded touch screen. It’s expected to be released next year.

Overall, total sales of hardware, games and accessories fell 14 percent in May to $743 million in U.S. physical retail stores. NPD blamed a light schedule for new game releases. NPD didn’t release May sales figures for the PS3 or Wii; the research firm leaves it to each company to disclose its data.