The pie charts illustrate
s the total electricity' s number in Australia and France in the field of fuel source over a 20 year from 1980 to 2000.
The pie charts illustrate the changes in the amount of fuel used in electricity generation in Australia and France from 1980 to 2000.
Overall, total electricity production in both countries
increaseincreased dramatically, while France' production doubled over a period of 20 years, Australia reckoned 70 % increase of the total production . Besides, the electricity sources were different in both countries under review.
You don't need to give data in your overview. Also, pay attention to the tense used in your essay.
This is not about the production of coal. It is about the electricity production generated from coal.
In comparison with the similar electricity source in France being accounted with 25 percent in both statistic' year , such trend showed a 80 percent increase.
The data are not given in percentage terms so this sentence is inaccurate. The rest of your body paragraphs also has the same problem.
A more detailed look at the pie charts revealed that the overall changes in percentages in Australia and France was not always similar.
I feel that this sentence does not add more value to your paragraph.