Crime in Waterloo went down for a third straight year in 2017, according to a release by the Waterloo Police Department yesterday. Calls for service handled by the department fell about 3%, from over 54,600 in 2016 to under 52,800 last year. City officials said the crime numbers were the lowest in decades, and Mayor Quintin Hart credits proactive public safety for adapting to the changing culture. According to the statistics, Group A offenses — about 30 serious crimes — dropped 8.1% over the last year, and Group B offenses, or disorderly conduct, trespassing and other minor crimes, decreased 2.16%. Total index crimes such as murder, robbery, aggravated assault, and auto theft were down from 2,214 reported in 2016 to 1,919 last year. Of the index crimes, aggravated assault saw the largest decrease with a 40% drop from 321 cases in 2016 to 191 in