What was the percentage change in Short-term investments between 2018 and 2019?
{"Cash and cash equivalents": {"2019": 5794, "2018": 4225, "Increase (Decrease)": 1569}, "Short-term investments": {"2019": 69, "2018": 155, "Increase (Decrease)": -86}, "": {"2019": 5863, "2018": 4380, "Increase (Decrease)": 1483}, "Percentage of total assets": {"2019": 30, "2018": 24, "Increase (Decrease)": ""}}
shortterm_investments_2019 = df["Short-term investments"]["2019"]
shortterm_investments_2018 = df["Short-term investments"]["2018"]
answer = (shortterm_investments_2019 - shortterm_investments_2018) / shortterm_investments_2018 * 100.0