CREATE TABLE table_37610 ("Date" TEXT, "Opponent" TEXT, "Score" TEXT, "Loss" TEXT, "Attendance" FLOAT, "Record" TEXT)

What is the attendance of the game that has the opponent of The Nationals with a record of 68-51?
SELECT SUM("Attendance") FROM table_37610 WHERE "Opponent" = 'nationals' AND "Record" = '68-51'
SELECT SUM("Attendance") FROM "table_37610" WHERE "Opponent" = 'nationals' AND "Record" = '68-51'