The given three bar charts describe
d about the average years of schooling, number of scientists and technicians, research and developmental spending in the years 1980 and1990 in developed and industrialized countries.
this should be written in present tense.... Also, you have not attached the charts and without any visual presentation it is difficult to grasp an idea about these bar charts. It is not clear whether all three parameters are meant for that particular duration.
From the chart the scientists and the technicians per thousand people was ten thousand and nineteen thousand in 1980 and 1990 respectively in developing countries.
Why do you say " per thousand people" ? .... this sounds very confusing. You better not include too many details in one sentence. That makes the reader confused. It would sound more clear if you split it to two or sentences.
You tend to make some grammar errors. Get rid of that though they may be minor errors.