CREATE TABLE table_204_394 (id DECIMAL, "year" DECIMAL, "album" TEXT, "label" TEXT, "peak chart\ positions\ us" DECIMAL, "peak chart\ positions\ us r&b" DECIMAL)

how long is the period between the first and last album in the table ?
SELECT MAX("year") - MIN("year") FROM table_204_394
SELECT MAX("year") - MIN("year") FROM "table_204_394"