|
| Year | Result | Explanatory Note |
|---|
| 2001 | 72.30 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year. |
| 2002 | 70.40 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year. |
| 2003 | 74.60 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year. |
| 2004 | 79.90 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year. |
| 2005 | 80.40 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year. |
| 2006 | 78.70 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year. |
| 2007 | 79.90 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year. |
| 2008 | 80.60 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year. |
| 2009 | 82.30 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year. |
| 2010 | 80.50 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year. |
| 2011 | 81.80 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year. |
| 2012 | 78.30 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year. |
| 2013 | 79.70 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year. |
| 2014 | 77.30 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year |
| 2015 | 80.90 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year |
| 2016 | 79.00 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year |
| 2017 | 85.30 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year |
| 2018 | 84.10 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year. |
| 2019 | 85.40 | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year. |
| 2020 | | This is a shared measure with the Virginia Department of Transportation. Data is provided by Old Dominion University from a test sample in June of each year. Test sample not taken in CY2020 due to COVID-19 pandemic. |
| 2021 | | |