SELECT "Country" FROM table_13975 WHERE "Change (08/07)" = 'unknown' AND "2008" > '1,102,497' AND "City" = 'luanda'
Which Country has a Change (08/07) of unknown, and a 2008 larger than 1,102,497, and a City of luanda?
CREATE TABLE table_13975 (
    "Country" text,
    "Airport" text,
    "City" text,
    "2008" real,
    "Change (08/07)" text
)