Database: california_schools
Question: What is the average number of test takers from Fresno schools that opened between 1/1/1980 and 12/31/1980?
SQL: SELECT AVG(T1.NumTstTakr) FROM satscores AS T1 INNER JOIN schools AS T2 ON T1.cds = T2.CDSCode WHERE strftime('%Y', T2.OpenDate) = '1980' AND T2.County = 'Fresno'