What is the total of win percentages when the year is 2008 and the crew is varsity 8+?
CREATE TABLE "season_by_season_results" (
  "year" text,
  "coach" text,
  "crew" text,
  "record" text,
  "win_pct" real
);
SELECT SUM("win_pct") FROM "season_by_season_results" WHERE "year"='2008' AND "crew"='varsity 8+';