What is the change in total income before income taxes between 2017 and 2018?
{"Domestic": {"2017": 75659, "2018": 85263, "2019": 215573}, "Foreign": {"2017": 99290, "2018": 107050, "2019": 117670}, "Total": {"2017": 174949, "2018": 192313, "2019": 333243}}
total_2018 = df["Total"]["2018"]
total_2017 = df["Total"]["2017"]
answer = total_2018 - total_2017