What was the change in APJ in 2019 from 2018?
{"Germany": {"2019": 3948, "2018": 3658, "2017": 3352}, "Rest of EMEA": {"2019": 8158, "2018": 7446, "2017": 7063}, "EMEA": {"2019": 12105, "2018": 11104, "2017": 10415}, "United States": {"2019": 9085, "2018": 7880, "2017": 7436}, "Rest of Americas": {"2019": 2109, "2018": 1832, "2017": 1911}, "Americas": {"2019": 11194, "2018": 9713, "2017": 9347}, "Japan": {"2019": 1180, "2018": 963, "2017": 885}, "Rest of APJ": {"2019": 3074, "2018": 2928, "2017": 2814}, "APJ": {"2019": 4254, "2018": 3891, "2017": 3699}, "SAP Group": {"2019": 27553, "2018": 24708, "2017": 23461}}
apj_2019 = df["APJ"]["2019"]
apj_2018 = df["APJ"]["2018"]
answer = apj_2019 - apj_2018