What was the percentage change in Net deferred tax assets between 2018 and 2019?
{"Deferred tax assets -- Stock based compensation": {"2019": 1757, "2018": 1337}, "Deferred tax assets -- Net operating loss and tax credit carryforwards": {"2019": 86879, "2018": 38622}, "Deferred tax assets -- Interest expense limitation": {"2019": 7620, "2018": "\u2014"}, "Deferred tax assets -- Pension obligation": {"2019": 13473, "2018": 3302}, "Deferred tax assets -- Excess and obsolete inventory": {"2019": 3217, "2018": 2161}, "Deferred tax assets -- Deferred revenue": {"2019": 3305, "2018": 6903}, "Deferred tax assets -- Employee bonuses and commissions": {"2019": 2537, "2018": 1874}, "Deferred tax assets -- Depreciation and amortization": {"2019": 29015, "2018": 29525}, "Deferred tax assets -- Operating lease liabilities": {"2019": 23451, "2018": "\u2014"}, "Deferred tax assets -- Other": {"2019": 9685, "2018": 9961}, "Deferred tax assets -- Deferred tax assets": {"2019": 180939, "2018": 93685}, "Deferred tax assets -- Less: Valuation allowance": {"2019": -76206, "2018": -30924}, "Deferred tax assets -- Net deferred tax assets": {"2019": 104733, "2018": 62761}, "Deferred tax liabilities -- Depreciation and amortization": {"2019": 41549, "2018": 17723}, "Deferred tax liabilities -- Unremitted earnings": {"2019": 4740, "2018": 3529}, "Deferred tax liabilities -- Operating lease right-of-use assets": {"2019": 22774, "2018": "\u2014"}, "Deferred tax liabilities -- Other": {"2019": 2966, "2018": 1267}, "Deferred tax liabilities -- Deferred tax liabilities": {"2019": 72029, "2018": 22519}, "Deferred tax liabilities -- Net deferred tax assets": {"2019": 32704, "2018": 40242}}
net_deferred_tax_assets_2019 = df["Deferred tax liabilities -- Net deferred tax assets"]["2019"]
net_deferred_tax_assets_2018 = df["Deferred tax liabilities -- Net deferred tax assets"]["2018"]
answer = ( net_deferred_tax_assets_2019 - net_deferred_tax_assets_2018 ) / net_deferred_tax_assets_2018 * 100.0