What is the total accrued tax liabilities between 2018 and 2019?
{"Accrued compensation and benefits": {"December 31, 2019": 12227, "December 31, 2018": 15283}, "Accrued tax liabilities": {"December 31, 2019": 4354, "December 31, 2018": 4455}, "Lease liabilities": {"December 31, 2019": 5109, "December 31, 2018": "\u2014"}, "Other": {"December 31, 2019": 6066, "December 31, 2018": 5553}, "Total accrued liabilities": {"December 31, 2019": 27756, "December 31, 2018": 25291}}
accrued_tax_liabilities_2019 = df["Accrued tax liabilities"]["December 31, 2019"]
accrued_tax_liabilities_2018 = df["Accrued tax liabilities"]["December 31, 2018"]
answer = accrued_tax_liabilities_2019 + accrued_tax_liabilities_2018