The given line graph depicts data on the changes in the amounts of CO2 a person emitted on average in 4 countries (the United Kingdom, Sweden, Italy and Portugal) between 1967 and 2007.
According to the line graph, in the United Kingdom the CO2 emissions reached a plateau at about 11 metric tonnes from 1967 until 1977. Subsequently, the figure showed a downward trend and eventually touched the lowest point at just under 9 metric tonnes in 2007. As regards Sweden, the figure for average CO2 emissions per person increased between 1967 and 1977, when it peaked at just over 10 metric tonnes. Then it steeply decreased until 1987, followed by a gradul decline until 2007.
With regard to the remaining countries, they showed different patterns from the aforementioned ones. In 1967, in Italy the CO2 emissions were just above 4 metric tonnes, whereas in Portugal the amounts were lower, at roughly 1. 2 metric tonnes. The figures for both countries rose progressively over the following period. From 1997 the amounts of CO2 emitted in Italy levelled off at just below 8 metric tonnes, while the ones emitted in Portugal still increased slightly, touching the highest point at approximately 5 metric tonnes in 2007.
Overall, it is clear that the United Kingdom produced the largest amounts of gas throughout the period in question, as opposed to Portugal, where a person emitted on average the least amounts of CO2. 
The  
given
 line graph depicts data on the  
changes
 in the  
amounts
 of CO2 a person  
emitted
 on average in 4 countries (the United Kingdom, Sweden, Italy and Portugal) between 1967 and 2007.
According to the line graph, in the United Kingdom the CO2 emissions reached a plateau at about 11 metric tonnes from 1967 until 1977.  
Subsequently
, the figure  
showed
 a downward trend and  
eventually
 touched the lowest point at  
just
 under 9 metric tonnes in 2007. As regards Sweden, the figure for average CO2 emissions per person increased between 1967 and 1977, when it peaked at  
just
 over 10 metric tonnes. Then it  
steeply
 decreased until 1987, followed by a  
gradul
 decline until 2007.
With regard to the remaining countries, they  
showed
  different
 patterns from the aforementioned  
ones
. In 1967, in Italy the CO2 emissions were  
just
 above 4 metric tonnes, whereas in Portugal the  
amounts
 were lower, at roughly 1. 2 metric tonnes. The figures for both countries rose  
progressively
 over the following period. From 1997 the  
amounts
 of CO2  
emitted
 in Italy levelled off at  
just
 below 8 metric tonnes, while the  
ones
  emitted
 in Portugal  
still
 increased  
slightly
, touching the highest point at approximately 5 metric tonnes in 2007. 
Overall
, it is  
clear
 that the United Kingdom produced the largest  
amounts
 of gas throughout the period in question, as opposed to Portugal, where a person  
emitted
 on average the least  
amounts
 of CO2.