The given line graph illustrates the height of males from four distinct nations from 1775 to 1975.
Overall, all four countries had represented fluctuations from year 1775 to 1875 before reporting an upward trend in the rest of the surveyed period. Moreover, the figure for France generally remained the lowest category for most time, while that for Denmark underwent the largest growth.
Regarding the period from 1775 to 1875, four nations witnessed a similar trend. The average height of the USA men started at around 167 centimetres in 1775, raking first, compared to only 160 centimetres from France, at the bottom. Following the data for the USA was the figure for Great Britain and Denmark, at 166 and 162 centimetres, respectively. During the next 100 years, the figure for Denmark, USA and Great Britain significantly fluctuated before returning to their initial figure in 1875. In contrast, the data for France witnessed a slight fluctuation, then increased to nearly 163 centimetres, surpassing that for Denmark.
Turning to the period from 1875 to 1975, these countries continued to report the same upward trend. The average height of males from the USA and Great Britain reached the same level of roughly 181 centimetres in 1975, while that for France climbed to around 173 centimetres in the same year. In comparison, the figure for Denmark men sharply surged to nearly 186 centimetres, overtaking the remaining three nations to become dominated category.