What was the percentage change in net investment in sales-type leases between 2018 and 2019?
{"Current minimum lease payments receivable(1)": {"December 31, 2019": 1201, "December 31, 2018": 11339}, "Non-current minimum lease payments receivable(2)": {"December 31, 2019": 889, "December 31, 2018": 1670}, "Total minimum lease payments receivable": {"December 31, 2019": 2090, "December 31, 2018": 13009}, "Less: Current unearned revenue(1)": {"December 31, 2019": 365, "December 31, 2018": 631}, "Less: Non-current unearned revenue(2)": {"December 31, 2019": 163, "December 31, 2018": 473}, "Net investment in sales-type leases": {"December 31, 2019": 1562, "December 31, 2018": 11905}}
net_investment_2019 = df["Net investment in sales-type leases"]["December 31, 2019"]
net_investment_2018 = df["Net investment in sales-type leases"]["December 31, 2018"]
answer = ( net_investment_2019 - net_investment_2018 ) / net_investment_2018 * 100.0