Number sequencing for journal header ids

When producing a data extract of all journals created between given dates in GL, posted and unposted, there are gaps in the sequencing of the internal je_header_id.  I need to produce a complete list for submission to auditors and cannot explain why there are so many gaps, over 1000 in one accounting period alone.  Is there another internal reference that I could use in my extract that would be more relevant?  i have already tried similar using batch_id but again there are multiple gaps.