user: Question: WHAT SEASON HAD A SEASON FINALE OF May 21, 1989 AND WAS VIEWED BY 17.98 MILLION HOUSEHOLDS?
Columns: ['Season', 'Episodes', 'Season premiere', 'Season finale', 'TV season', 'Rank', 'Households (millions)']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'real']
Sample row: [1.0, 22.0, 'September 30, 1984', 'April 21, 1985', '1984/85', '#8', 17.06]
SQL:

assistant: SELECT "Season" FROM "Table" WHERE "Season finale" = 'May 21, 1989' AND "Households (millions)" < 17.98;