Link -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
It's not surprising at all that the Mac households also have Windows boxes. Obviously Windows has the marketshare and has had for quite a number of years. If the MAC marketshare is going up, this means that people who used to own Windows have more recently purchased a MAC. And I think quite a few people keep their older computers around...for secondary machines, machines for their kids, etc.
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