A major part of the fall in oil prices last year was driven by concerns over the rising production levels of Iran. With nuclear sanctions in place, Iran had been forced to significantly curtail production due to lack of buyers. Once those sanctions disappeared due to the Iranian nuclear deal, the country was prepared to begin exporting crude en masse once more. That outcome caused investors to panic and led oil prices to fall considerably.
Analysts reassured the markets that it would take a couple of years for Iran to get production back to pre-sanctions levels. Almost all of this conventional wisdom has turned out to be incredibly wrong.
Iranian oil production has rebounded much faster than many analysts ever anticipated as the chart below shows. At this point, Iran is roughly back to pre-sanctions production levels. Score one against analysts who expected the process to take years.