The line graph illustrates the percentage of good quality rivers in four different countries ( Wales, Northern Ireland, England and Scotland ) from 1990 to 2002.
Overall, it is clear that there was an upward trend in the percentage of quality water in three of the countries, except for Wales. Although, Wales had the highest percentage of rivers classificed as being good quality at the beginning, this figure showed a significant decline by the end of the period.
Looking at the graph in more detail, Wales had the highest percentage of rivers that was categorized as having good chemical quality, at around 95% in the initial year. Then this figure remained unchanged until 1998, before showing a significant decrease to 80% by 2002. In contrast, the figure for Northern Ireland started at around 85%. After experiencing a gradual rise, it reached its peak of 97% by the end of the period.
As for the remained countries, the figure for England was approximately 45% in 1990. Subsequently, it witnessed a moderate growth with some fluctuations, at 70% in 1996. In 2002, this index hit its a peak of 50%, after fell to 30%. Similarly, the Scotland river began at 20%, before experiencing a dramatic increase to 50% in 2000. Finally, this figure dropped to 40% in 2002.