-- Database schema
| divisions : division [ TEXT ] primary_key , name [ TEXT ] , country [ TEXT ] | matchs : Div [ TEXT ] matchs.Div = divisions.division , Date [ DATE ] , HomeTeam [ TEXT ] , AwayTeam [ TEXT ] , FTHG [ INTEGER ] , FTAG [ INTEGER ] , FTR [ TEXT ] , season [ INTEGER ] |
-- -- What percentage of matches played on 2005/07/30 belong to the F1 division?

SELECT CAST(SUM(CASE WHEN Div = 'F1' THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(Div) FROM matchs WHERE Date = '2005-07-30' ;