CREATE TABLE table_76998 ("Week" FLOAT, "Date" TEXT, "Opponent" TEXT, "Result" TEXT, "Kickoff Time" TEXT, "Attendance" TEXT)

What is the average number of weeks that the opponent was the Denver Broncos?
SELECT AVG("Week") FROM table_76998 WHERE "Opponent" = 'denver broncos'
SELECT AVG("Week") FROM "table_76998" WHERE "Opponent" = 'denver broncos'