user: Question: What is the attendance of the game that has the opponent of The Nationals with a record of 68-51?
Columns: ['Date', 'Opponent', 'Score', 'Loss', 'Attendance', 'Record']
Types: ['text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['August 1', '@ Braves', '9-0', 'James', 32238.0, '61-49']
SQL:

assistant: SELECT "Attendance" FROM "Table" WHERE "Opponent" = 'Nationals' AND "Record" = '68-51';