CREATE TABLE table_name_23 (evaluation_average__before_april_2009_ VARCHAR(255), peak_lessons_taught VARCHAR(255), _percentage_of_negative_evaluations VARCHAR(255))
What is the mean Evaluation number (before April 2009) when the Peak lessons taught was less than 80 and the negative percentage of evaluations was 0.8%?
    
SQL: SELECT evaluation_average__before_april_2009_ FROM table_name_23 WHERE peak_lessons_taught < 80 AND _percentage_of_negative_evaluations = "0.8%"