Estimates from both the American Community Survey (ACS) and the Current Population Survey (CPS) are being made available. Data estimates from the ACS are used in the KIDS COUNT Data Book Child Well-being Index. They reflect single-year data though are only available back to 2008 when the health insurance question was first added to the survey. Because of issues of small sample size, the CPS estimates reflect 3-year averages. Even with a 3-year average, the ACS is considered a more reliable data source for state-level estimates. We continue to post the 3-year CPS estimates because they are available for a longer time series which may be more useful for certain data analyses.
For more detailed information about differences between the two sources of health insurance data, see notes from the Census Bureau, found here: http://www.census.gov/hhes/www/hlthins/about/index.html.