{"pre_text": ["supplementary information on oil and gas producing activities ( unaudited ) 2018 proved reserves decreased by 168 mmboe primarily due to the following : 2022 revisions of previous estimates : increased by 84 mmboe including an increase of 108 mmboe associated with the acceleration of higher economic wells in the u.s .", "resource plays into the 5-year plan and an increase of 15 mmboe associated with wells to sales that were additions to the plan , partially offset by a decrease of 39 mmboe due to technical revisions across the business .", "2022 extensions , discoveries , and other additions : increased by 102 mmboe primarily in the u.s .", "resource plays due to an increase of 69 mmboe associated with the expansion of proved areas and an increase of 33 mmboe associated with wells to sales from unproved categories .", "2022 production : decreased by 153 mmboe .", "2022 sales of reserves in place : decreased by 201 mmboe including 196 mmboe associated with the sale of our subsidiary in libya , 4 mmboe associated with divestitures of certain conventional assets in new mexico and michigan , and 1 mmboe associated with the sale of the sarsang block in kurdistan .", "2017 proved reserves decreased by 647 mmboe primarily due to the following : 2022 revisions of previous estimates : increased by 49 mmboe primarily due to the acceleration of higher economic wells in the bakken into the 5-year plan resulting in an increase of 44 mmboe , with the remainder being due to revisions across the business .", "2022 extensions , discoveries , and other additions : increased by 116 mmboe primarily due to an increase of 97 mmboe associated with the expansion of proved areas and wells to sales from unproved categories in oklahoma .", "2022 purchases of reserves in place : increased by 28 mmboe from acquisitions of assets in the northern delaware basin in new mexico .", "2022 production : decreased by 145 mmboe .", "2022 sales of reserves in place : decreased by 695 mmboe including 685 mmboe associated with the sale of our canadian business and 10 mmboe associated with divestitures of certain conventional assets in oklahoma and colorado .", "see item 8 .", "financial statements and supplementary data - note 5 to the consolidated financial statements for information regarding these dispositions .", "2016 proved reserves decreased by 67 mmboe primarily due to the following : 2022 revisions of previous estimates : increased by 63 mmboe primarily due to an increase of 151 mmboe associated with the acceleration of higher economic wells in the u.s .", "resource plays into the 5-year plan and a decrease of 64 mmboe due to u.s .", "technical revisions .", "2022 extensions , discoveries , and other additions : increased by 60 mmboe primarily associated with the expansion of proved areas and new wells to sales from unproven categories in oklahoma .", "2022 purchases of reserves in place : increased by 34 mmboe from acquisition of stack assets in oklahoma .", "2022 production : decreased by 144 mmboe .", "2022 sales of reserves in place : decreased by 84 mmboe associated with the divestitures of certain wyoming and gulf of mexico assets .", "changes in proved undeveloped reserves as of december 31 , 2018 , 529 mmboe of proved undeveloped reserves were reported , a decrease of 17 mmboe from december 31 , 2017 .", "the following table shows changes in proved undeveloped reserves for 2018 : ( mmboe ) ."], "post_text": ["."], "table": [["beginning of year", "546"], ["revisions of previous estimates", "47"], ["extensions discoveries and other additions", "61"], ["dispositions", "-19 ( 19 )"], ["transfers to proved developed", "-106 ( 106 )"], ["end of year", "529"]], "table_ori": [["Beginning of year", "546"], ["Revisions of previous estimates", "47"], ["Extensions, discoveries, and other additions", "61"], ["Dispositions", "(19)"], ["Transfers to proved developed", "(106)"], ["End of year", "529"]]}

Question: what was the net decrease in proved undeveloped reserves for 2018 : ( mmboe ) ?
Evidence:
table_5: beginning of year the end of year of 546 is 529 ;
table_0: beginning of year the beginning of year of 546 is 546 ;
Program: subtract(529, 546)
Answer:
str_answer: -17
exe_answer: -17