What is the increase / (decrease) in the orders for Asia and Australia from 2018 to 2019?
{"Europe, C. I. S., Africa, Middle East": {"2019": 46086, "2018": 46495, "Actual": -1, "Comp.": -1}, "therein: Germany": {"2019": 12021, "2018": 11254, "Actual": 7, "Comp.": 7}, "Americas": {"2019": 29812, "2018": 25060, "Actual": 19, "Comp.": 14}, "therein: U.S.": {"2019": 21166, "2018": 18106, "Actual": 17, "Comp.": 10}, "Asia, Australia": {"2019": 22101, "2018": 19742, "Actual": 12, "Comp.": 11}, "therein: China": {"2019": 8989, "2018": 8459, "Actual": 6, "Comp.": 6}, "Siemens": {"2019": 97999, "2018": 91296, "Actual": 7, "Comp.": 6}, "therein: emerging markets1": {"2019": 31720, "2018": 30564, "Actual": 4, "Comp.": 4}}
asia_australia_2019 = df["Asia, Australia"]["2019"]
asia_australia_2018 = df["Asia, Australia"]["2018"]
answer = asia_australia_2019 - asia_australia_2018