CREATE TABLE table_3668 ("#" FLOAT, "Title" TEXT, "Timeslot" TEXT, "Air date" TEXT, "Viewers  ( 000s ) " FLOAT, "Weekly Rank Sky1" FLOAT, "Weekly Rank Virgin Media" FLOAT)

What was the weekly rank by Virgin media for the title aired on May 20, 2010?
SELECT MIN("Weekly Rank Virgin Media") FROM table_3668 WHERE "Air date" = 'May 20, 2010'
SELECT MIN("Weekly Rank Virgin Media") FROM "table_3668" WHERE "Air date" = 'May 20, 2010'