What was the percentage change in values of properties between 2018 and 2019?
{"": {"30 June 2019": 0, "30 June 2018": 0}, "Right-of-use assets* -- Properties": {"30 June 2019": 68569, "30 June 2018": 5070}, "Right-of-use assets* -- Motor Vehicles": {"30 June 2019": 259, "30 June 2018": "-"}, "Right-of-use assets* -- Connectivity Links": {"30 June 2019": 9696, "30 June 2018": "-"}, "Right-of-use assets* -- ": {"30 June 2019": 78524, "30 June 2018": 5070}}
properties_2019 = df["Right-of-use assets* -- Properties"]["30 June 2019"]
properties_2018 = df["Right-of-use assets* -- Properties"]["30 June 2018"]
answer = ( properties_2019 - properties_2018 ) / properties_2018 * 100.0