The first bar graph provides information regarding the rates of marriage and divorce in USA from 1970 to 2000, while the second chart compares between the percentage of adult American based on their marital status in 1970 and that of in 2000.
you don't need to put comma here, you just need to use comma when you put 'while' in the beginning of your sentence, not in the middle like this
Generally, the number of marriage tended to decrease over the three decades while divorce rate experienced fluctuation.
this is the right example, you didn't put comma because you put comma in the middle of the sentence