How much did the win rate increase for the team after getting the No.1 NBA draft pick in the 2003 season than previous season?
No.1 draft pick refers to draftRound = 1; in the 2003 season refers to draftyear = 2003; increase = subtract(divide(sum(won), add(sum(won), sum(lost))) where draftyear = 2004, divide(sum(won), add(sum(won), sum(lost))) where draftyear = 2003)
SELECT (CAST(SUM(CASE WHEN T1.year = 2004 THEN T1.won ELSE 0 END) AS REAL) / SUM(CASE WHEN T1.year = 2004 THEN T1.won + T1.lost ELSE 0 END)) - (CAST(SUM(CASE WHEN T1.year = 2003 THEN T1.won ELSE 0 END) AS REAL) / SUM(CASE WHEN T1.year = 2003 THEN T1.won + T1.lost ELSE 0 END)) FROM teams AS T1 INNER JOIN draft AS T2 ON T1.tmID = T2.tmID WHERE T2.draftRound = 1 AND T2.draftYear = 2003