Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Year | Driver | Nation of citizenship | Racing series | Type of vehicle |
| --- | --- | --- | --- | --- |
| 1993.0 | Nigel Mansell | United Kingdom | Formula One | Open wheel |
| 1994.0 | Nigel Mansell | United Kingdom | CART | Open wheel |
| 1995.0 | Al Unser, Jr. | United States | CART | Open wheel |
| 1996.0 | Jeff Gordon | United States | NASCAR | Stock car |
| 1997.0 | Jimmy Vasser | United States | CART | Open wheel |
| 1998.0 | Jeff Gordon | United States | NASCAR | Stock car |
| 1999.0 | Jeff Gordon | United States | NASCAR | Stock car |
| 2000.0 | Dale Jarrett | United States | NASCAR | Stock car |
| 2001.0 | Bobby Labonte | United States | NASCAR | Stock car |
| 2002.0 | Michael Schumacher | Germany | Formula One | Open wheel |
| 2003.0 | Tony Stewart | United States | NASCAR | Stock car |
| 2004.0 | Dale Earnhardt, Jr. | United States | NASCAR | Stock car |
| 2005.0 | Michael Schumacher | Germany | Formula One | Open wheel |
| 2006.0 | Tony Stewart | United States | NASCAR | Stock car |
| 2007.0 | Jeff Gordon | United States | NASCAR | Stock car |
| 2008.0 | Jimmie Johnson | United States | NASCAR | Stock car |
| 2009.0 | Jimmie Johnson | United States | NASCAR | Stock car |
| 2010.0 | Jimmie Johnson | United States | NASCAR | Stock car |
| 2011.0 | Jimmie Johnson | United States | NASCAR | Stock car |
| 2012.0 | Tony Stewart | United States | NASCAR | Stock car |
| 2013.0 | Ryan Hunter-Reay | United States | IndyCar Series | Open wheel |
Question:
What Nation of citizenship has a stock car vehicle with a year of 2012?
Answer:
United States