What percentage of the total gain in book amount was due to internally generated software?
{"Movements": {"Rights and licences": 0, "Internally generated software": 0, "Software under development": 0, "Total": 0}, "30 June 2019 -- Opening net book amount at 1 July 2018": {"Rights and licences": 13, "Internally generated software": 6385, "Software under development": 6509, "Total": 12907}, "30 June 2019 -- Additions  internally developed": {"Rights and licences": "-", "Internally generated software": "-", "Software under development": 11896, "Total": 11896}, "30 June 2019 -- Amortisation": {"Rights and licences": "-", "Internally generated software": -1116, "Software under development": "-", "Total": -1116}, "30 June 2019 -- Transfers between classes": {"Rights and licences": "-", "Internally generated software": 2121, "Software under development": -2121, "Total": "-"}, "30 June 2019 -- Disposals": {"Rights and licences": "-", "Internally generated software": -9, "Software under development": "-", "Total": -9}, "30 June 2019 -- Closing net book amount": {"Rights and licences": 13, "Internally generated software": 7381, "Software under development": 16284, "Total": 23678}}
total_closing = df["30 June 2019 -- Closing net book amount"]["Total"]
total_openning = df["30 June 2019 -- Opening net book amount at 1 July 2018"]["Total"]
internally_generated_software_closing = df["30 June 2019 -- Closing net book amount"]["Internally generated software"]
internally_generated_software_openning = df["30 June 2019 -- Opening net book amount at 1 July 2018"]["Internally generated software"]
answer = (internally_generated_software_closing - internally_generated_software_openning) / (total_closing - total_openning) * 100.0