SELECT "1981 Census" FROM table_15978 WHERE "City" = 'Livorno'
What's the 1981 census of Livorno?
CREATE TABLE table_15978 (
    "#" real,
    "City" text,
    "1981 Census" real,
    "1991 Census" real,
    "2001 Census" real,
    "2010 Est." real,
    "Region" text
)