- = No Data Reported;
-- = Not Applicable;
NA = Not Available;
W = Withheld to avoid disclosure of individual company data.
W -- Individual state volumes are withheld to avoid disclosure of operator-level reserves data, due to statistical precision requirements, or due to other data quality reasons. The individual state volumes are included in the U.S. Total volume.
See Definitions, Sources, and Notes link above for more information on this table.