CREATE TABLE table_21043 ("Poll Source" TEXT, "Dates administered" TEXT, "Democrat: Vivian Davis Figures" TEXT, "Republican: Jeff Sessions" TEXT, "Lead Margin" FLOAT)

On July 31, 2008, what are the Democrat: Vivian Davis Figures percentages?
SELECT "Democrat: Vivian Davis Figures" FROM table_21043 WHERE "Dates administered" = 'July 31, 2008'
SELECT "Democrat: Vivian Davis Figures" FROM "table_21043" WHERE "Dates administered" = 'July 31, 2008'