What percentage was the total unit sales of store no.10 to the total sales of its weather station on 2014/10/31?
store no.10 refers to store_nbr = 10; on 2014/10/31 refers to date = '2014-10-31'; percentage = Divide (Sum(units where store_nbr = 10), Sum(units)) * 100
SELECT CAST(SUM(CASE WHEN T2.store_nbr = 10 THEN units * 1 ELSE 0 END) AS REAL) * 100 / SUM(units) FROM sales_in_weather AS T1 INNER JOIN relation AS T2 ON T1.store_nbr = T2.store_nbr WHERE T1.`date` = '2014-10-31'