From the 2008 National Health Interview Survey:
On average, how many hours of sleep do you get in a 24-hour period?
Participants were asked how many hours they sleep during a 24-hour period. The numerator data includes those participants reporting the following number of hours of sleep per day for their age group: 8+ hours for those aged 18-21 years and 7+ hours for those aged 22 years and over.
The target was revised from 70.9 to 70.8 due to a change in the rounding rules for target calculations of Minimal Statistical Significance.