From the 2007 Health Information National Trends Survey:
In the past 12 months, have you done the following things while using the Internet?
Kept track of personal health information, such as care received, test results, or upcoming medical appointments?
[NUMERATOR AND DENOMINATOR:]
Do you ever go on-line to access the Internet or World Wide Web, or to send and receive e-mail?
HINTS is a biennial, cross-sectional survey of a nationally-representative sample of American adults that is used to assess the impact of the health information environment.