user: Question: What is the average year of the most recent appearance of the Boston Crusaders, who had their first appearance after 1976?
Columns: ['Corps Name', 'Number of Finals Appearances', 'Year of First Appearance', 'Year of Most Recent Appearance', 'All Years of Finals Appearances']
Types: ['text', 'real', 'real', 'real', 'text']
Sample row: ['Santa Clara Vanguard', 42.0, 1972.0, 2013.0, '1972–2013']
SQL:

assistant: SELECT AVG("Year of Most Recent Appearance") FROM "Table" WHERE "Year of First Appearance" > 1976.0 AND "Corps Name" = 'Boston Crusaders';