The line graph illustrate the proportion of water in UK rivers which was classified as having good chemical quality from 1990 to 2002.
Overall, what stands out is that northern Ireland, England, and Scotland followed an upward trend, while Wales showed the opposite pattern. It is also evident that England an Scotland fluctuated over the period.
In 1990, Wales recorded the highest figure at approximately 95%, whereas northern Ireland stood at around 83%. In contrast, England and Scotland were significantly lower, at about 45% and 21% respectively. Over the next few years, Wales decreased sharply to 80% in 2002 before remained relatively stable until 1998. Meanwhile, northern Ireland experienced the same trend as Wales until 1998, but later it fell slightly to 98% by the end of the period after showed the gradual increase at about 100% in 2000.
In terms of England, its figure grew gradually to 69% in 1996 before showed a dramatical decline to 30% in 1998. However the figure for England increased to 50% in 2002. As for Scotland, it experienced a noticeable decline at 40% at the end of the period after increased significantly to 60% in 2000.