From the Behavioral Risk Factor Surveillance System (BRFSS) Assessment, 2010:
[NUMERATOR:] States that identify caregivers of people with disabilities in the BRFSS.
People may provide regular care or assistance to a friend or family member who has a health problem, long-term illness, or disability. During the past month, did you provide any such care or assistance to a friend or family member? <Yes, No, Don't know, Not sure, Refused>
[denominator:] States and Districts that are officially part of the United States.