Iranian oil either:
- Declined sharply by 500kbd when OPEC cut back last fall, and has remained there since (JODI - Iranian self reports),
- Barely declined, and in any case quickly recovered to almost the same level (EIA), or
- Began a steady decline in 2006 long before the OPEC cuts, that more or less has continued since (Oil and Gas Journal)
Welcome to the wonderful world of oil statistics analysis... Half a million barrels/day - 12% - in discrepancy.