Ya know, maybe it’s not the economic slowdown. Google CEO Eric Schmidt said January 31 that the company was feeling no pain from any macroeconomic softening.

Maybe the novelty of Google search is wearing thin because it doesn’t return what people are looking for.

Maybe Google should go work on its algorithms some more because comScore says US growth in Google’s click-through rate, up 25%-40% last year, which was only a few weeks ago, is now non-existent.

None in January and a mere 3% year-over-year in February and clicks on ad-supported links are what Google depends on for revenue.

Of course these are US-only numbers. International could pull Google out.

But plain old Google searches that have nothing to do with paid clicks are also down 5% or 6% although Google’s share of the market is supposed to be up from 58.5% to 59.2% with Yahoo and Microsoft both down.

Wall Street, which is trying to figure out what’s going on and how much credence to put in comScore’s numbers, has been adjusting its Google metrics and cutting its price targets for the stock that would be $1,000. Right now Google can’t manage $450.

Google, which attributed the January slowdown to its attempts to improve the quality of clicks and tighten up on accidental clicks, reports April 17.

Some analysts are holding that thought. If the quality of the clicks gets better, it can charge advertisers more.