pre_text: Share-based Compensation Expense We have several share-based compensation plans covering stock options and RSUs for our employees and directors, which are described more fully in Note 11. We measure our compensation cost related to share-based payment transactions based on fair value of the equity or liability classified instrument. For purposes of estimating the fair value of each stock option unit on the date of grant, we utilize the Black-Scholes option-pricing model. Option valuation models require the input of highly subjective assumptions including the expected volatility factor of the market price of our common stock (as determined by reviewing our historical public market closing prices). Our accounting for share-based compensation for RSUs is based on the closing market price of our common stock on the date of grant. Our total share-based compensation expense recognized in the Company’s results of operations from non-cash and cash-portioned instruments issued to our employees and directors comprised the following (in thousands):
table: Year Ended December 31,
table: 2019 2018
table: Research and development expense:
table: Stock option awards $8 $38
table: RSU awards 13 27
table: 21 $65
table: General and administrative expense:
table: Stock option awards 12 61
table: RSU awards 105 104
table: 117 $165
table: Total share-based compensation expense 138 $230
question: Analyse this data from a financial earnings document. How much did the stock-based compensation expense in the general and administrative operations decreased from 2018 to 2019?