Tim Cook may not have seen the latest numbers. Or perhaps he’s just more modest than Steve Jobs was. But he understated matters somewhat when he told the press last week that the Mac outgrew the PC market almost six times in the year ending in June and that it had outpaced its competitors every single quarter for five years.

In fact, according to reports issued Wednesday by Gartner and IDC, the Mac has outgrown the industry for 22 quarters in a row. And its edge last quarter was considerably greater than 6 to 1. Gartner has Mac shipments in the U.S. growing faster than the market by a factor of nearly 20 to 1. According to IDC, the ratio is more like 80 to 1.

According to Gartner’s press release:

“Gartner’s early study shows that Apple experienced the strongest growth among the top five vendors in the U.S. PC market. Apple’s PC shipments increased 21.5 percent in the third quarter of 2011. The robust growth of the MacBook Air continued to lead Apple’s overall growth in the U.S. market.”

Gartner has Apple’s (AAPL) share of the U.S. PC market  in Q3 at 12.9%. IDC puts it at 11.3%, behind Hewlett Packard (HPQ) at 28.6% and Dell (DELL) at 21.9%.

Those numbers would be very different, of course, if either research firm counted the iPad as a computer. Both both acknowledge in their reports that iPad sales had cut into the PC market — at least among Apple’s competitors.

Gartner: “The popularity of non-PC devices, including media tablets, such as the iPad and smartphones, took consumers’ spending away from PCs.”

IDC’s David Daoud refers to the phenomenon as “iPad cannibalization.”

UPDATE: Several readers have pointed out that when you back Mac shipments out of Gartner and IDC’s numbers, the rest of the PC market actually shrank last quarter. Viewed this way, Apple’s growth compared with its competitors approaches infinity.

Below the fold: Gartner’s and IDC’s spreadsheets for the U.S. and worldwide markets.