This statistic, as you might imagine, annoys storage executives as much as the flossing number annoys dentists.

That explains why Seagate , the world’s largest hard drive maker, is hoping to reverse the trend. Though the company traditionally had been content to sell raw storage to others for use in their wares (everything from Xboxes to data centers), executives are pushing to get their own branded backup products onto retail shelves. They were eager to show me stylish new plug-in FreeAgent drives for Macs and PCs that they announced this week, and to explain why they’re launching a TV marketing campaign during football games and Oprah to tout them. (Seagate studies found that, once reminded of backup’s virtues, people were twice as likely to say they’d buy drives.)

Honestly, backup’s virtues are easy to appreciate. After all, what if you have a power surge that fries your home appliances, or your hard drive fails or a hurricane hits? Do you really want to lose all those digital photos and baby videos? Of course not. But as in that scene from Jerry Maguire, the storage industry’s pleas to help us help ourselves seem to fall on deaf ears. “Even in Silicon Valley,” says Box.net’s Levie, “I think if you ask the average person at a tech company, they don’t back up.”

This reluctance hasn’t stopped tech giants from getting into the consumer storage game. Just this year, enterprise heavyweight EMC bought Iomega for about $213 million, and online storage provider Mozy for $76 million. Security specialist Symantec bought SwapDrive for $124 million. Hewlett-Packard launched its Upline online storage service this spring, and Dell partnered with Box.net this summer to provide online backup on its Inspiron Mini 9 laptop.

Why the sudden surge into storage? In the age of broadband, digital downloads and online sharing, companies have noticed that more of the stuff people care about is getting stockpiled in bits rather than in boxes. Consider the proliferation of iPods, iPhones, Tivos , photos, and video on sites like YouTube.

Analysts estimate that 70 percent of this content will be stored by individuals, not corporations – suggesting a market ripe for backup drives that often start at around $150, and paid online services that start at about $5. “We had to either decide we were going to ignore this whole thing,” an EMC executive told me, “or jump in.”

But the fact that big companies are leaping into online storage doesn’t mean consumers will. New marketing campaigns notwithstanding, most PC users seem to have rejected the traditional plug-in, back-up process that Seagate and some others have begun selling. And it’s not clear whether online backup services will fare much better; though Wi-Fi makes online backup easy to do, most home Internet connections are so slow that the first session can take hours.

Though no one has yet solved the backup hassle, the closest thing so far may be Apple’s most recent efforts, Time Capsule and Time Machine. A wireless router and hard drive in one, Time Capsule works with Apple’s latest operating system to invisibly archive your files, so that if you lose something, software called Time Machine lets you drive your computer backward, Back to the Future-style, to the day when you know you last had it.

When Apple studied backup habits a couple of years ago, it found that more than 90 percent of its customers failed to regularly copy their data for safekeeping – even though they were storing more sentimental content on their Macs. Why? “It’s not because they didn’t know that backup was important,” says Jai Chulani, senior product manager for Time Capsule. “It was ‘Oh, it’s too hard to do. I have to constantly plug things in.’ ”

Apple says Time Machine is one of the most popular features in its latest operating system, OS X Leopard; and in Apple’s online store Time Capsule is the 5th most popular Mac-related item, ahead of the Mac mini and Mac Pro computers.

But don’t expect those features to become common for the masses of Microsoft Windows users anytime soon. Because Apple controls both the hardware and the software in its Mac universe, its engineers could more easily invent an automatic backup system. (UPDATE: A reader reminds me of Microsoft’s Windows Home Server, which has many features of Time Capsule, plus remote access. Thanks for jogging my memory; I wrote about it here.)

For others, it would be more difficult to build – though one can imagine a Windows-based system that marries Google’s desktop search program with a wireless external drive for automatic data protection. Such a solution would be nifty – and even easier than flossing.