The given line graph illustrates how many European people of various age groups went to the gym from 1990 to 2010.
Overall, the percentages of all age groups witnessed an upward trend. Furthermore, the proportions of people aged 18-23 and 24-33 underwent fluctuations over the whole period.
Starting at nearly 16% in 1990, the proportion of European people aged 24-33 was the highest amongst the four groups, followed closely by citizens aged 18-23 (15%). Both the proportion of 24-33 year olds and 18-23 year olds went up sharply in the first interval of four years before experiencing fluctuations in the next time. However, in the last year, the percentage of people aged 24-33 was approximately 8% higher than that of individuals aged 18-23.
In terms of people aged 34-43 and 44-53, both the percentages of these two groups increased gradually until the end of the period. In particular, at the beginning, the proportion of citizens aged 34-43 was 1% higher than that of middle-aged people. After the course of 20 years, the percentage of people aged 34-43 and individuals aged 44-53 accounted for 10% and 6% respectively.