What is the percentage change in non-cash share-based compensation expense from 2018 to 2019?
{"": {"2019": "(Dollars in thousands)", "2018": "", "2017": "", "2016": "", "2015": ""}, "Gross Profit": {"2019": 114197, "2018": 89990, "2017": 72416, "2016": 60371, "2015": 54649}, "Depreciation expense (a)": {"2019": 6370, "2018": 6089, "2017": 5791, "2016": 4028, "2015": 2566}, "Plant start-up expense (b)": {"2019": "\u2014", "2018": "\u2014", "2017": "\u2014", "2016": 1628, "2015": "\u2014"}, "Non-cash share-based compensation (c)": {"2019": 922, "2018": 859, "2017": 243, "2016": 221, "2015": 201}, "Adjusted Gross Profit": {"2019": 121489, "2018": 96938, "2017": 78450, "2016": 66248, "2015": 57416}, "Adjusted Gross Profit as a % of Net Sales": {"2019": 49.4, "2018": 50.2, "2017": 51.5, "2016": 51.1, "2015": 50.6}}
noncash_sharebased_compensation_2019 = df["Non-cash share-based compensation (c)"]["2019"]
noncash_sharebased_compensation_2018 = df["Non-cash share-based compensation (c)"]["2018"]
answer = ( noncash_sharebased_compensation_2019 - noncash_sharebased_compensation_2018 ) / noncash_sharebased_compensation_2018 * 100.0