What was the percentage change in rights and licences between 2018 and 2019?
{"": {"30 June 2019": 0, "30 June 2018": 0}, "Rights and licences": {"30 June 2019": 13, "30 June 2018": 13}, "Internally generated software": {"30 June 2019": 7381, "30 June 2018": 6385}, "Software under development": {"30 June 2019": 16284, "30 June 2018": 6509}, "Total intangible assets": {"30 June 2019": 23678, "30 June 2018": 12907}}
rights_licences_2019 = df["Rights and licences"]["30 June 2019"]
rights_licences_2018 = df["Rights and licences"]["30 June 2018"]
answer = (rights_licences_2019 - rights_licences_2018) / rights_licences_2018 * 100.0