The recent spate of cyberattacks on retailers has scared shoppers and triggered debates on Capitol Hill about whether consumers' data is being properly protected. Despite its security flaws, the retail sector isn't the one most vulnerable to breaches. That dubious honor goes to health care. A study of all data breaches in 2013 (pdf) found that the health-care sector suffered the highest share of attacks last year, overtaking the business sector for the first time in almost a decade. The Identity Theft Resource Center, a nonprofit organization that tracks data theft, reported that health-care organizations suffered 267 breaches last year, or 43 percent of all attacks in 2013.