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
database name:db_id authors
Author table Author Cols: Id dtype integer, Name dtype text, Affiliation dtype text, 
Conference table Conference Cols: Id dtype integer, ShortName dtype text, FullName dtype text, HomePage dtype text, 
Journal table Journal Cols: Id dtype integer, ShortName dtype text, FullName dtype text, HomePage dtype text, 
Paper table Paper Cols: Id dtype integer, Title dtype text, Year dtype integer, ConferenceId dtype integer, JournalId dtype integer, Keyword dtype text, 
PaperAuthor table PaperAuthor Cols: PaperId dtype integer, AuthorId dtype integer, Name dtype text, Affiliation dtype text, 
