The given graph delineates the income gap between male and female in five distinct nations from 1978 to 2008.
In general, the income difference between genders in all countries followed downward trends, except Australia. In addition, Japan had the highest income gap between genders over the period.
Looking at the details, in 1978, there was a difference of approximately 50% between the incomes of men and women in Japan. This figure then gradually fell to about 40% in 2008, though remaining as the biggest gap of incomes between genders. Following the same trend, the income difference in the US was 34%, compared to 30% that of the UK in 1978. These categories then both slightly decreased to 26% and 27% in 2008, respectively.
Regarding the remaning categories, the gap between the incomes of male and female in France was 20% in 1978 before declining to about 18% in 2008. However, the figure for Australia started at 19% in 1978, then rose to about 22% at the end of the period, surpassing that of France to become the second-lowest income gap.