Plaxo Inc., the company behind the automatically syncing address book service, released a report today about how people deal with contact information, based on a study of U.S. smartphone users.

Its Mobile & Online Backup Trends Study found that 66 percent of U.S. smartphone users store both professional and personal contacts in the same address book. With 35 percent of American adults owning a smartphone, that represents a lot of people who wish they had done a better job of tagging the entries in their contacts.

Plaxo found lots of information that must have made their executives happy, such as 71 percent of smartphone users keep their contacts on their device, and that 20 percent of these consumers would be willing to pay $500 or more to guarantee not losing this contact information.

Reliance on remote access to contacts is growing, too, with 24 percent using the cloud to back up this personal data.

As always with studies like these, the factoids give a different kind of insight into user behavior. Of the third who have lost or damaged their smartphone, 19 percent of them dropped it in a toilet. Having a child trash it and leaving it behind at a restaurant or in a taxi are the next most common tragedies, with 7 percent losing it at a concert.

There must be some fascinating stories behind the 53 percent who simply said, “other,” not to mention the 2 percent who reported having suffered five or more such smartphone disasters.

“These survey results reinforce the trend around an increasingly untethered world,” said Preston Smalley, general manager for Plaxo.  “Even though people are on the go more and more, they have not lowered their expectations around access to their latest updated data including their address book, and in fact, have increased expectations.”