What is the average revenue from Singapore in 2018 and 2019?
{"Belgium": {"2019": 49, "2018": 64}, "France": {"2019": 40, "2018": 154}, "China": {"2019": 359, "2018": 512}, "Russia": {"2019": 2, "2018": 302}, "Germany": {"2019": 36, "2018": 143}, "Italy": {"2019": 159, "2018": 110}, "South Korea": {"2019": "-", "2018": 314}, "Singapore": {"2019": 215, "2018": 376}, "Other": {"2019": 525, "2018": 469}, "": {"2019": 1361, "2018": 2444}}
singapore_2019 = df["Singapore"]["2019"]
singapore_2018 = df["Singapore"]["2018"]
russia_2019 = df["Russia"]["2019"]
answer = ( singapore_2019 + singapore_2018 ) / russia_2019