What was the change in bunkers’ consumption and other voyage expenses from 2018 to 2019?
{"Brokers commissions on revenue": {"2017": 6456, "2018": 7555, "2019": 7527}, "Bunkers consumption and other voyage expenses": {"2017": 8948, "2018": 12819, "2019": 16245}, "Total": {"2017": 15404, "2018": 20374, "2019": 23772}}
bunkers_consumption_and_other_voyage_expenses_2019 = df["Bunkers consumption and other voyage expenses"]["2019"]
bunkers_consumption_and_other_voyage_expenses_2018 = df["Bunkers consumption and other voyage expenses"]["2018"]
answer = bunkers_consumption_and_other_voyage_expenses_2019 - bunkers_consumption_and_other_voyage_expenses_2018