CREATE TABLE table_63668 ("School" CLOB, "City" CLOB, "Team Name" CLOB, "Enrollment 08-09" FLOAT, "IHSAA Class" CLOB, "IHSAA Class Football" CLOB, "County" CLOB, "Year Joined  ( Or Joining ) " FLOAT, "Previous Conference" CLOB)

What year did the team from City of Aurora join?
SELECT AVG("Year Joined (Or Joining)") FROM table_63668 WHERE "City" = 'aurora'
SELECT AVG("Year Joined (Or Joining)") FROM "table_63668" WHERE "City" = 'aurora'