As the answer by Astralbee correctly points out, "rose" is the past tense of the verb "to rise", while "risen" is the past participle of that verb. The past participle is used in forming both the past perfect and present perfect constructions. The sentence
(1) The percentage of the employees has risen from 20 percent to 24 percent over the past five years.
uses the present perfect. This consists of the present tense of the verb "to have" plus the past participle of the main verb. (see This page on "Present Perfect" for details.)
As the EF page linked above puts it, the present perfect is often used for:
- An action or situation that started in the past and continues in the present.
- An action performed during a period that has not yet finished.
- A repeated action in an unspecified period between the past and now.
- An action that was completed in the very recent past, expressed by 'just'.
- An action when the time is not important.
However, an action that occurred at a specified time in the past that ended significantly before the present will not usually be described using the present perfect. It will most often be described using the simple past, although the past perfect or other constructions may sometimes be used.
Thus sentence (1) is proper and natural. This construction is often used for events during a period still in progress, or one very recently ended. This is true whether the rise may be assuemned to be continuing, or to have only recently halted. But an attempt to use this construction about a definite past period not ending at or near the present movement (or continuing beyond the present) would not be. For example:
(2) The percentage of the employees has risen from 20 percent to 24 percent during the 1990s.
is not a valid use of this construction. One might write either of:
- (3) The percentage of the employees had risen from 20 percent to 24 percent
- (4) The percentage of the employees rose from 20 percent to 24 percent during the 1990s. during the 1990s.
Sentence (3) would be likely to be used only if some other event, subsequent to the rise, had been or was about to be mentioned as well.
One might also write:
(5) The percentage of the employees has risen from 20 percent to 24 percent over the past five years, but that rise reversed dramatically last November.
This is a case where the rise has recently endued, but the present perfect may still be used.