user: Question: What is the total number of tiers for the postseason of Semifinalist?
Columns: ['Season', 'Tier', 'League', 'Pos.', 'Postseason', 'European competitions']
Types: ['text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['2007–08', 4.0, 'RegionalLiga', 3.0, '–', '–']
SQL:

assistant: SELECT SUM("Tier") FROM "Table" WHERE "Postseason" = 'Semifinalist';