The line graph illustrates the reported number of influenza cases among people aged over 65 in a particular village in the UK over a ten-year period, from 1985 to 1995.
Overall, the number of flu cases showed significant fluctuation over the decade, but the general trend was a modest increase, with the figures ending slightly higher in 1995 than in 1985. The peak number of cases was recorded in 1991.
In 1985, the recorded number of cases started at approximately 40 people. This figure rose steadily to reach a minor peak of around 55 in 1987, before dropping back to nearly 45 in 1988. Following this, there was a sharp recovery, reaching about 55 cases again in 1989.
The most dramatic period occurred between 1989 and 1991. The number of reported cases increased steeply, peaking at around 75 in 1991. After this high point, the figures fell sharply in the following year to about 60 in 1992. The number remained relatively stable for the next two years, fluctuating slightly between 60 and 65 in 1993 and 1994. In the final year shown, 1995, the number of influenza cases finished at exactly 60, which was 20 cases higher than the starting point in 1985.