What was the percentage change in the Total Net Asset Value (NAV) in 2019 from 2018?
{"Net Asset Value per share -- Total vessel values including newbuildings (broker values)": {"2019": 1801.5, "2018": 1675.1, "2017": 1661.1}, "Net Asset Value per share -- Committed CAPEX on newbuildings": {"2019": -51.2, "2018": -258.0, "2017": -306.9}, "Net Asset Value per share -- Cash position": {"2019": 72.5, "2018": 127.4, "2017": 134.2}, "Net Asset Value per share -- Loans receivables": {"2019": 4.6, "2018": "-", "2017": "-"}, "Net Asset Value per share -- Bunkers": {"2019": 34.8, "2018": 39.4, "2017": 33.2}, "Net Asset Value per share -- Freight receivables": {"2019": 89.8, "2018": 86.0, "2017": 71.3}, "Net Asset Value per share -- Other receivables": {"2019": 6.2, "2018": 7.5, "2017": 11.8}, "Net Asset Value per share -- Other plant and operating equipment": {"2019": 4.3, "2018": 3.0, "2017": 1.9}, "Net Asset Value per share -- Land and buildings": {"2019": 8.1, "2018": "-", "2017": "-"}, "Net Asset Value per share -- Investments in joint ventures": {"2019": 1.2, "2018": 0.1, "2017": 0.3}, "Net Asset Value per share -- Prepayments": {"2019": 3.5, "2018": 2.9, "2017": 4.4}, "Net Asset Value per share -- Borrowings": {"2019": -863.4, "2018": -754.7, "2017": -753.9}, "Net Asset Value per share -- Trade payables": {"2019": -47.1, "2018": -35.1, "2017": -26.2}, "Net Asset Value per share -- Other liabilities": {"2019": -47.3, "2018": -36.5, "2017": -33.8}, "Net Asset Value per share -- Current tax liabilities": {"2019": -1.5, "2018": -1.0, "2017": -1.4}, "Net Asset Value per share -- Total Net Asset Value (NAV)": {"2019": 1016.0, "2018": 856.1, "2017": 796.0}, "Net Asset Value per share -- Total number of shares excluding treasury shares (million)": {"2019": 74.4, "2018": 73.9, "2017": 62.0}, "Net Asset Value per share -- Total Net Asset Value per share (NAV/share) (USD)": {"2019": 13.6, "2018": 11.6, "2017": 12.8}}
nav_2019 = df["Net Asset Value per share -- Total Net Asset Value (NAV)"]["2019"]
nav_2018 = df["Net Asset Value per share -- Total Net Asset Value (NAV)"]["2018"]
answer = (nav_2019 - nav_2018) / nav_2018 * 100.0