Richmond, Virginia:

Law and finance have long been driving forces in the economy. The city is home to both the United States Court of Appeals for the Fourth Circuit, one of 13 United States courts of appeals, and the Federal Reserve Bank of Richmond, one of 12 Federal Reserve Banks, as well as offices for international companies such as Genworth Financial, CapitalOne, Philip Morris USA, and numerous other banks and brokerages. Richmond is also home to four of the largest law firms in the United States: Hunton & Williams, McGuireWoods, Williams Mullen, and LeClairRyan. Another law firm with a major Richmond presence is Troutman Sanders, which merged with Richmond-based Mays & Valentine LLP in 2001.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". When did the Troutman Sanders-Mays & Valentine LLP merger occur?
2001