What percentage of papers were preprinted after the year 2000?
after the year 2000 refers to Year > 2000; preprinted refers to ConferenceId = 0 AND JournalId = 0; percentage refers to DIVIDE(COUNT(ConferenceId = 0 AND JournalId = 0 AND Year > 2000), COUNT(Id))
SELECT CAST(SUM(CASE WHEN Year > 2000 THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(Id) FROM Paper