What is the increase/ (decrease) in Accrued vacation pay deducted when paid from 2018 to 2019?
{"Non-current deferred tax assets: -- Reserve for uncollectible accounts": {"2019": 1194, "2018": 1164}, "Non-current deferred tax assets: -- Accrued vacation pay deducted when paid": {"2019": 4152, "2018": 4371}, "Non-current deferred tax assets: -- Accrued expenses and deferred revenue": {"2019": 9839, "2018": 12848}, "Non-current deferred tax assets: -- Net operating loss carryforwards": {"2019": 86535, "2018": 76659}, "Non-current deferred tax assets: -- Pension and postretirement obligations": {"2019": 80245, "2018": 84786}, "Non-current deferred tax assets: -- Share-based compensation": {"2019": 693, "2018": 9}, "Non-current deferred tax assets: -- Derivative instruments": {"2019": 5868, "2018": -825}, "Non-current deferred tax assets: -- Financing costs": {"2019": 176, "2018": 189}, "Non-current deferred tax assets: -- Tax credit carryforwards": {"2019": 6077, "2018": 6411}, "Non-current deferred tax assets: -- ": {"2019": 194779, "2018": 185612}, "Non-current deferred tax assets: -- Valuation allowance": {"2019": -6680, "2018": -9158}, "Non-current deferred tax assets: -- Net non-current deferred tax assets": {"2019": 188099, "2018": 176454}, "Non-current deferred tax liabilities: -- Goodwill and other intangibles": {"2019": -66271, "2018": -82992}, "Non-current deferred tax liabilities: -- Basis in investment": {"2019": -5, "2018": -12}, "Non-current deferred tax liabilities: -- Partnership investments": {"2019": -16138, "2018": -14425}, "Non-current deferred tax liabilities: -- Property, plant and equipment": {"2019": -278712, "2018": -267154}, "Non-current deferred tax liabilities: -- ": {"2019": -361126, "2018": -364583}, "Non-current deferred tax liabilities: -- Net non-current deferred taxes": {"2019": -173027, "2018": -188129}}
accrued_vacation_pay_deducted_2019 = df["Non-current deferred tax assets: -- Accrued vacation pay deducted when paid"]["2019"]
accrued_vacation_pay_deducted_2018 = df["Non-current deferred tax assets: -- Accrued vacation pay deducted when paid"]["2018"]
answer = accrued_vacation_pay_deducted_2019 - accrued_vacation_pay_deducted_2018