I tend to write long and complex sentences that usually leads to many mistakes. Any advice on how to write better and more complex sentences error free? What do you think about these sentences? Caution when using the word 'respectively'.

Whereas 80 percent of domestic students achieved second class degree or higher in Art History, only 70 percent of foreign students achieved the same results. Similarly, in English literature, more than 70 percent of national students achieved second class or higher degree in contrast to international students, who received only 60 percent. On the other hand, 80 percent and 85 percent (pick one, 80 or 85 percent) of international students and almost 60 percent of UK students scored second degree or higher in both Electrical Engineering and Information Technology. Further, the percentage of national and international students who scored second degree class or higher was comparable, as they scored 74 percent and 60 percent respectively. Finally, the scores for Nursing, Accountancy, and Sociology were 78 percent.