The line graph illustrates the proportion of river water in the UK rivers that classified as having great chemical quality from 1990 to 2002.
In general, there was a noticeable increase in the percentage of river water quality in the UK in Northern Ireland, England, and Scotland, while the data for Wales show a downward trend. Notably, the figure for Wales was higher than that for the country throughout the period shown, except between 2000 and 2002.
Analyzing the information in greater detail, in 1990, about 95% of river water with good chemical quality in Wales, compared to approximately 88% in Northern Ireland. Over the subsequent 8 years, the proportion of river water quality in the UK in Wales remained unchanged, before decreasing to around 80% in 2002. On the other hand, the UK saw a significant climb in the percentage of river water that is classified as having good chemical quality, reaching 95% at the end of the period.
Turning to the other countries, the proportion of river water quality in the UK in England stood at 45% in 1990, followed by Scotland at 22%. Over the next 8 years, the figure for England declined gradually to roughly 30% in 1998, but rose rapidly to just under 50% in 2002. Finally, the percentage of river water quality in the UK in Scotland increased considerably to 40% in the final year.