The electricity generation was dominated by coal in New Zealand while Germany prefered other sources

Electricity Generation by Source in New Zealand and Germany

The pie charts compare the sources of electricity generation in two countries from 1980 to 2010. Overall, it can be seen that the electricity generation in New Zealand was dominated by coal, while nuclear, natural gas, and coal also was popular sources in Germany. In addition, the total of electricity generation in these countries rose twice over 30-year period.

In New Zealand, the source was dominated by coal. The number stood at 56 in 1980, then it rocketed roughly three times in the 20-year later. Also, hydro experienced a rise. The number started at 30 and rose slowly to 46 units. However, other sources as such natural gas and petroleum declined to 2 units in 2010, whereas the numbers showed at 30 and 11 respectively in the first year.

In any other country, there was nuclear which rocketed almost eight times from 20 to 155. Similiarly, the total of petroleum also inclined over the period, represented at 22 in 1980 and 27 at the end of this period. However, coal which was produced by Germany remained stable at 28 units. Further, this country resulted natural gas and hydro whose total dropped significantly. The number of natural gas stood at 28 and inclined to 2 units in 2010, while a decrease by 5 units experienced by the rate of hydro.

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while nuclear, natural gas, and coal also was popular sources in Germany. - First, the word "also" doesn't sound proper here - you've never mention nuclear and natural gas before, so you can't you use "also". In addition to this, replace was with were.

In New Zealand, the source was dominated by coal - this sentence requires some work. - you can write something like - The coal was the dominating type of electric generation or The coal was the main source of electricity.

as such natural gas - such as

whereas the numbers showed at 30 and 11 respectively in the first year. - I didn't get the meaning of this

In any other country, there was nuclear which rocketed almost eight times from 20 to 155. -- Where is the information? You are not allowed to make asumptions. Moreover, i think rocked is not the approtiate word here - try to replace it with increased/went up/exceeded ....

also inclined over the period - dictionary.cambridge.org/dictionary/english/inclined