Nearly 12 percent of U.S. computer-owning households now own a Mac, according to an NPD Group released Monday.

That's up from just 9 percent in 2008, according to the latest Household Penetration Study from market research firm NPD.

The survey suggests that Mac use is on the rise. The study also found that 85 percent of Mac-using households also own Windows PCs.

Meanwhile, 66 percent of those households contain three or more computers, compared with 29 percent for Windows households.

Additionally, Mac users are about twice as likely to also have many common consumer electronics, such as iPods, DSLRs, large LCD HDTVs, or GPS navigation systems.

Unsurprisingly, Mac users tend to have a higher cash flow than average.

While Apple owners tend to own more computers and more electronics devices, there is also a high correlation among Apple owners and more affluent consumer households, said Stephen Baker, vice president of industry analysis, said in a statement.

Thirty-six percent of Apple computer owners reported household incomes greater than $100,000, compared to 21 percent of all consumers.