New numbers from comScore Networks show a very slight month-over-month increase in Microsoft's search market share in the U.S. -- hitting 8.5 percent, compared with 8.3 percent the month before. Tiny as that is, it might seem like a small bit of good news in the Redmond company's long struggle against Google. But a longer view reveals a different picture.

Going back to the middle of last year, Microsoft's share of the market is down noticeably, as reflected in our chart above, which aggregates comScore's publicly released data. The company's U.S. market share was above 12 percent back in the summer of 2007. Google's share has risen 7 percentage points in roughly the same time frame, now sitting just under 63 percent.

Microsoft saw some slight increases along the way -- thanks in part to its Live Search Club, which offers prizes to people who play games that incorporate search queries; and its Live Search cashback program, which offers partial refunds to people who use the company's search engine to buy selected products. More recently, Microsoft unveiled a Live Search Perks program that offers prizes based on the number of searches participants conduct through the Live Search engine. That was in early October, so the effect of that promotion isn't yet reflected in the public comScore data.

But overall, those initiatives haven't had a lasting impact on Microsoft's share of the market. With Yahoo's share price stuck below $13 -- compared with Microsoft's January acquisition offer of $31 per share -- it will be interesting to see if the Redmond company feels compelled to make another attempt at a deal. Yahoo's search market share is still above 20 percent, according to comScore.

(For the record, a Bloomberg News story yesterday reporting a decline in Microsoft's share for September appears to have been based on an incorrect number for the previous month. The numbers above are direct from comScore senior analyst Andrew Lipsman.)