What is the average number of cities of markets with low film market estimate bigger than 10000?
SELECT avg(T2.Number_cities) FROM film_market_estimation AS T1 JOIN market AS T2 ON T1.Market_ID  =  T2.Market_ID WHERE T1.Low_Estimate  >  10000
Düşük film pazarı tahminine sahip ortalama pazarların ortalama şehir sayısı 10000'den daha büyük?