premise: There were 13,584 housing units at an average density of 1,154.7 per square mile (445.8/km²), of which 4,360 (35.8%) were owner-occupied, and 7,824 (64.2%) were occupied by renters. The homeowner vacancy rate was 2.0%; the rental vacancy rate was 6.5%.  9,458 people (34.0% of the population) lived in owner-occupied housing units and 15,849 people (57.0%) lived in rental housing units.
hypothesis: rental vacancy rate was higher