Table 2. Rental and Homeowner Vacancy Rates, by Area: First Quarter 2004 and 2005 Rental vacancy rates First First 90-Percent Area quarter quarter Confidence Interval (+)a 2004 2005 of 2005 rate of difference United States.......... 10.4 10.1 0.4 0.5 Inside Core-Based Statistical Areas.. NA 10.1 0.5 NA In central cities.. NA 10.4 0.6 NA Not in central cities (suburbs).......... NA 9.7 0.7 NA Outside Core-Based Statistical Areas.. NA 9.7 1.5 NA Northeast............. 7.9 7.2 0.7 0.8 Midwest............... 12.3 12.2 0.9 1.0 South................. 12.7 12.2 0.9 1.0 West.................. 7.6 7.5 0.8 0.9 Homeowner vacancy rates First First 90-Percent Area quarter quarter Confidence Interval (+)a 2004 2005 of 2005 rate of difference United States.......... 1.7 1.8 0.1 0.1 Inside Core-Based Statistical Areas.. NA 1.8 0.1 NA In central cities.. NA 2.0 0.3 NA Not in central cities (suburbs).......... NA 1.7 0.2 NA Outside Core-Based Statistical Areas.. NA 1.9 0.3 NA Northeast............. 0.9 1.8 0.3 0.3 Midwest............... 2.1 2.3 0.3 0.3 South................. 2.0 1.9 0.2 0.3 West.................. 1.3 1.2 0.2 0.3 aA 90-percent confidence interval is a measure of an estimate's reliability. The larger the confidence interval is, in relation to the size of the estimate, the less reliable the estimate. NA Not available. Core-Based Statistical Area data for 2005 and later are not comparable to earlier data. Beginning in first quarter 2005, the Current Population Survey/Housing Vacancy Survey is using the new metropolitan and micropolitan statistical definitions which were announced by the Office of Management and Budget (OMB) in June 2003, and were based on the application of the 2000 standards to Census 2000 data. OMB announced updates as of December 2003, based on application of the 2000 standards to more recent Census Bureau estimates. The December 2003 definitions are available at: https://www.census.gov/population/www/estimates/metrodef.html.