MARION — Marion’s police department is trying to keep up with the demands that come with serving a rapidly growing population, paying two to nine times more on overtime for its officers than other similarly sized departments in Iowa to cover more patrols and increased calls for service, according to city records examined by The Gazette. Bettendorf, for example, spent $73,000 in its 2015 budget year. But with an understaffed department and its own dispatch center, paying out thousands in overtime has become a reality for Marion year after year.