New stats from comScore are out, and as seen by the research firm, it seems the December search market was an eventful place.  Google and Bing both managed to increase their market shares, while Yahoo saw a somewhat substantial drop occur.

Let’s start at the top.  According to comScore, Google’s market share rose to 66.6 percent, putting it a rounded decimal point away from being the search engine used by two-thirds of Americans (if you figure that 66 and two-thirds would round up to 66.7).

What’s more, Google’s market share rose from 66.2 percent between November and December, meaning it made a real gain, and didn’t just sort of oscillate.

As for Yahoo, its share decreased from 16.4 percent to 16.0 percent in the same period, which could be something shareholders will interrogate Carol Bartz about when the company delivers its first-quarter earnings report.

Finally, Bing’s market share rose from 11.8 percent to 12.0 percent on a month-over-month basis, and while that’s good, it obviously wasn’t enough to put the Bing-Yahoo joint venture up on the whole.

All this may be something Google’s shareholders bring up soon enough, too, but with a rather different perspective than Yahoo’s supporters.