How many turnovers per game did the assist champion had in the 2003 NBA season?
turnovers per game = avg(turnovers); 2003 refers to year = 2003; NBA refers to lgID = 'NBA'
SELECT AVG(T2.turnovers) FROM players AS T1 INNER JOIN players_teams AS T2 ON T1.playerID = T2.playerID WHERE T2.year = 2003 GROUP BY T1.playerID, T2.assists ORDER BY T2.assists DESC LIMIT 1