CREATE TABLE table_15621 ("Heat" FLOAT, "Lane" FLOAT, "Name" TEXT, "Nationality" TEXT, "Time" TEXT)

How many lanes have a Nationality of united states, and a Name of aaron peirsol?
SELECT COUNT("Lane") FROM table_15621 WHERE "Nationality" = 'united states' AND "Name" = 'aaron peirsol'
SELECT COUNT("Lane") FROM "table_15621" WHERE "Name" = 'aaron peirsol' AND "Nationality" = 'united states'