The number and percentage of optinal columns in base tables

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SELECT Count(*) FILTER (WHERE C.is_nullable='YES') AS number_of_optional_columns, 
Count(*) AS number_of_columns, 
Round(Count(*) FILTER (WHERE C.is_nullable='YES')::decimal*100/Count(*)::decimal,1) AS percentage_of_optional_columns
FROM information_schema.columns C INNER JOIN information_schema.tables T USING (table_schema, table_name)
INNER JOIN information_schema.schemata S ON T.table_schema = S.schema_name
WHERE T.table_type = 'BASE TABLE' 
AND (T.table_schema = 'public' OR S.schema_owner<>'postgres');