What is the percentage change in the revenue in Australia from 2018 to 2019?
{"": {"AUSTRALIA": 0, "ASIA": 0, "TOTAL": 0}, "30 June 2019 -- Revenue": {"AUSTRALIA": 149295, "ASIA": 4864, "TOTAL": 154159}, "30 June 2019 -- Non-current assets1": {"AUSTRALIA": 44061, "ASIA": 15899, "TOTAL": 59960}, "30 June 2018 -- Revenue": {"AUSTRALIA": 174776, "ASIA": 2155, "TOTAL": 176931}, "30 June 2018 -- Non-current assets1": {"AUSTRALIA": 49235, "ASIA": 15245, "TOTAL": 64480}}
revenue_2019 = df["30 June 2019 -- Revenue"]["AUSTRALIA"]
revenue_2018 = df["30 June 2018 -- Revenue"]["AUSTRALIA"]
answer = (revenue_2019 - revenue_2018) / revenue_2018 * 100.0