What is the percentage of offense rebounds from the total rebounds of the players in year 2000.
in year 2000 refers to year = 2000; percentage = divide(sum(o_rebounds), sum(rebounds)) * 100%
SELECT CAST(SUM(T2.o_rebounds) AS REAL) * 100 / SUM(T2.rebounds) FROM players_teams AS T1 INNER JOIN player_allstar AS T2 ON T1.playerID = T2.playerID WHERE T1.year = 2000