The pie chart compares (pie charts compare - there are three charts)regarding the percentage of degree (degrees - there are four degrees) granted in different sectors (these aren't sector but degrees) at the national University (National - it is a noun) between 1990 and 2010.
In general, there was an upward trend(this is not a line nor a bar graph that you will use "upward" to describe your trend) of major Computer Science, whilst major of Business experienced(this term is very sensational) a gradual decrease througout (wrongly spelled - throughout) the period. Medicine fluctuates (use simple past - 1990-2000) by 5% as the same with Law before returning to their first figures. (If this is your general trend, do not add specific details)
To start with,(Delete - unnecessary) in 1990, computer science (Noun - capitalize the first letters) had the percentage at 30 percent which virtually with the proportion of business (Your statement is confusing. Reword it) . Then, the percentage of medicine and law had a quarter and 15 percent respectively. (Medicine, Law)
Ten years later, (By 2000) most degrees were given to the computer science sec tor (typo error?) at 40% (Most degrees were given? Do not talk about degrees but the grant that each of the degrees received). Likewise, degrees in medicine saw a 5% increase. Business and law degrees were awarded less than in 1990 at 20 % and 10 % respectively. (Organize your ideas and sentences well)
In 2010, Computer Science was still the most popular choice amongst graduates (Do not include your own opinion. It is true that the grant of Computer Science increase, however, we do not know if it is popular among students) with almost half of all degrees granted. Medicine reverts back like in 1990 at 25% whist (typo error?) Business and Law are at 15%.
This is how I would write the essay based on the way you have written it.
The pie charts compare the proportion of courses granted at the National University in three decades. In general, the grant awarded to Computer Science significantly increased by almost 50 percent in the last decade.
In 1990, the figure for Computer Science and Business were the same, at 30 percent, while Law received the lowest grant, at only 15 percent. The grant given to Computer Science increased by 10 percent in 2000. Similarly, Medicine saw a five percent grant increase, while Business and Law decreased significantly, at 20 percent and 10 percent respectively.
By 2010, the grant for Computer Science increased even more at almost 50 percent, whereas the figure for Medicine decreased by five percent. On the other hand, Business and Law degrees each saw a similar proportion of grant, at 15 percent.
Please delete the word regarding in the first sentence. You also want to discuss the percentages of degrees and not use the term major. For example, when referring to the trends you want to say computer science degree to give recognition to the completion of the degree as indicated in these pie charts. There is a misspelling. In the second sentence change it to, "throughout this period".
When you compare medicine and law, this is a good observation. However, you may want to give dates. For example, the pie chart shows the same trend in degrees granted with a fluctuation of 5% in 2000, but a return to their original figure in 2010. If you give dates, the comparison is easier to follow.
It seems as if computer science and business had the same percentage of degrees granted in 1990. However, this is not clear because you add the word virtually. The next sentence I would change a quarter to 25% and 15 percent to 15%. Then I would add a comma between the percent sign and respectively. This will make it easier to read.
If this needs to be typed, please be careful about the spaces between the numbers and percent sign. Also, there is a space between a word that needs to be closed. Please change sec tor to sector. When you use respectively, this is really good. However, remember to place a comma before respectively.
I think you should use a transition word such as, However or Yet, before the beginning of the sentence regarding the degrees granted in medicine. When you describe medicine reverting back don't use the word like. There should be a comma after 25% and whist should be changed to while.
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