What was the percentage change in customer incentives between 2018 and 2019?
{"Customer incentives": {"Note": 6, "30 June 2019 $'000": 1091, "30 June 2018 $'000": 1145}, "Capitalised transaction costs": {"Note": "", "30 June 2019 $'000": 3359, "30 June 2018 $'000": 5490}, "Contract costs": {"Note": 6, "30 June 2019 $'000": 448, "30 June 2018 $'000": "-"}, "Total other assets - non-current": {"Note": "", "30 June 2019 $'000": 4898, "30 June 2018 $'000": 6635}}
customer_incentives_2019 = df["Customer incentives"]["30 June 2019 $'000"]
customer_incentives_2018 = df["Customer incentives"]["30 June 2018 $'000"]
answer = (customer_incentives_2019 - customer_incentives_2018) / customer_incentives_2018 * 100.0