human
Considering the provided database schema and associated query, produce SQL code to retrieve the answer to the query. 
###Database Schema: Municipality, No. of Barangays, Area (km²), Population (2010), Pop. density (per km²), Income Class (2004)
###Question: List the population density per kilometer for the city of abra de ilog.
gpt
SELECT Pop. density (per km²) FROM table WHERE Municipality = Abra de Ilog