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

The line graph illustrates the amound of CO2 emitted by each person in 4 nations from 1967 to 2007. Generally speaking, the UK person released the largest amount of CO2 for the whole period researched. Besides, it can be noticed that Italy and Portugal had a steady rise in CO2 emissions of all years, while that of the UK and Sweden dropped within a time span of 40 years. Getting back to the details, in 1967, about 11 tonnes CO2 was produced by a UK citizen, followed by 9 tonnes in Sweden. In comparison, each Italian discharged over 4 tonnes which was approximately threefold higher than that of a Portuguese. From that time onwards, the average quantity of CO2 released in the UK decreased gradually to under 9 tonnes at the end of the period, while the figure for Sweden, after an 2 tonnes climb in the first decade, also went down moderately to well under 6 tonnes in 2007. In contrast, more CO2 was produced by each person in Italy whose figure grew to nearly 8 tonnes in 2007, compared with an equally significant increase to roughly 6 tonnes in Portugal.