user: Question: What is the quantity preserved of the E-1 class?
Columns: ['Class', 'Wheel arrangement', 'Fleet number(s)', 'Year made', 'Quantity made', 'Quantity preserved']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['4-6-0 — ooOOO', '4-6-0 — ooOOO', '4-6-0 — ooOOO', '4-6-0 — ooOOO', '4-6-0 — ooOOO', '4-6-0 — ooOOO']
SQL:

assistant: SELECT "Quantity preserved" FROM "Table" WHERE "Class" = 'E-1';