U.S. 2010 census figures are 3.3 million wheelchair users over the age of 15. That's up about 50% from 2000. I don't have a figure on how many of those are powered chairs, but the incidence of stress injury in people who use wheelchairs every day is high, (neck and shoulder strain, carpal tunnel, etc) so power wheelchair use is common and on the rise.
According to the VA study I just posted, 40% of power wheelchair users have great difficulty dealing in controlling them.
Here is a link to the complete study if you want to read it:
In other words, the market is HUGE. And that's not even considering the international market. A Japanese producer of wheelchairs will be dealing with the international market.
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