Summarise the information by selecting and reporting the main features, and make comparisons where relevant.

The bar chart illustrates the estimated amount of oil produced (*) in 6 countries between 1990 and 2010, measured in millions of barrels per day.  

Overall, oil production capacity tended to increase during this 20-year period. 

The figures for Saudi Arabia were significantly higher than in the other countries, while production was lowest in Qatar. 

From 1990 to 2010, there was a significant increase in oil production in Saudi Arabia. 

In 1990, just over 8 million barrels per day were produced and this rose steadily, reaching a peak of over 14 million barrels per day in 2010. 

In contrast, the smallest producer was Qatar. 

Despite a slight increase in 2000, production in Qatar remained relatively stable at less than 1 million barrels per day. 

The other countries saw a slight rise in oil production over the period. 

The estimated figure for Iran in 1990 was over 3 million barrels per day, compared with around 2 million barrels in the other three countries. 

Although production did not increase in 2000 in the UAE, the amount of oil produced peaked in 2010 in Iran at over 4 million barrels and at almost 4 million barrels in Iraq, Kuwait and the UAE.