What was the change in stock-based compensation between 2018 and 2019?
{"Net income (loss)": {"2019": 18398, "2018": 16617, "2017": -7904}, "Investment income": {"2019": -5258, "2018": -2256, "2017": -1691}, "Interest expense": {"2019": 16726, "2018": 10280, "2017": 9896}, "Income tax provision (benefits)": {"2019": -1330, "2018": 10681, "2017": -1563}, "Depreciation and amortization": {"2019": 20016, "2018": 22957, "2017": 23469}, "Stock-based compensation": {"2019": 11029, "2018": 9298, "2017": 7833}, "Impairment loss and equity in net loss of affiliate": {"2019": 6787, "2018": 1411, "2017": 1284}, "Loss on extinguishment of debt": {"2019": 2033, "2018": "-", "2017": "-"}, "Acquisition and integration related expenses": {"2019": 935, "2018": "-", "2017": 4513}, "Non-recurring legal expenses, net of reversal of litigation -- provision": {"2019": -11020, "2018": 10738, "2017": 9192}, "Non-recurring legal expenses, net of reversal of litigation -- Gain on LoJack battery performance legal Settlement": {"2019": -18333, "2018": -28333, "2017": "-"}, "Non-recurring legal expenses, net of reversal of litigation -- Restructuring": {"2019": 8015, "2018": "-", "2017": "-"}, "Non-recurring legal expenses, net of reversal of litigation -- Other": {"2019": 217, "2018": 989, "2017": 4339}, "Non-recurring legal expenses, net of reversal of litigation -- Adjusted EBITDA": {"2019": 48215, "2018": 52382, "2017": 49368}}
stockbased_compensation_2019 = df["Stock-based compensation"]["2019"]
stockbased_compensation_2018 = df["Stock-based compensation"]["2018"]
answer = stockbased_compensation_2019 - stockbased_compensation_2018