Source -The number of US households that own a Mac has increased to 12 percent. That's up from just 9 percent in 2008, according to the latest "Household Penetration Study" from market research firm NPD. The survey confirms recent trends that suggest Mac use is on the rise, though those sources don't always agree on the exact number. And, interestingly enough, 85 percent of Mac-using households also own Windows PCs.
Macs in 12% of US households, majority also have Windows PCs - Ars Technica