What was the change in current year increases between 2017 and 2018?
{"Balance as of January 1,": {"2019": 282.4, "2018": 131.0, "2017": 45.9}, "Current year increases": {"2019": 104.3, "2018": 157.8, "2017": 87.2}, "Write-offs, recoveries and other (1)": {"2019": -223.4, "2018": -6.4, "2017": -2.1}, "Balance as of December 31,": {"2019": 163.3, "2018": 282.4, "2017": 131.0}}
current_year_increases_2018 = df["Current year increases"]["2018"]
current_year_increases_2017 = df["Current year increases"]["2017"]
answer = current_year_increases_2018 - current_year_increases_2017