What was the change in Personnel reduction costs between 2017 and 2018?
{"Personnel reduction costs": {"2019": 2823, "2018": 12587, "2017": 2214}, "Relocation and exit costs": {"2019": 5956, "2018": 2256, "2017": 3190}, "Restructuring charges": {"2019": 8779, "2018": 14843, "2017": 5404}}
personnel_reduction_2018 = df["Personnel reduction costs"]["2018"]
personnel_reduction_2017 = df["Personnel reduction costs"]["2017"]
answer = personnel_reduction_2018 - personnel_reduction_2017