Here are some suggestions for you. A couple of minor details depend on which editorial style you are following. It looks like you might be following an APA or Chicago author-date citation system, so I'll edit for you in APA and make notes about Chicago's preferences where they are different.
Suggested deletions are in strike-through text. Suggested insertations are in bold, blue text. Editorial notes are in italics and should be deleted after they are addressed
It steadilyincreased steadily thereafter, and it attained a level ofreaching US$233 billion USD in2004, which is substantially larger thanexceeded the corresponding value of cash dividends substantially (by 18%).
Notes about these suggested changes:
1. In scholarly writing, try not to begin a sentence with the word it. Although the word might seem clear to you, usually the word is unclear to readers (or at least it is potentially ambiguous or forces the reader to stop and checking for meaning, creating a halted, cumbersome reading experience). Using a more specific word generally creates a smoother transition and allows the reader to move smoothly into the next idea. For these reasons, I recommend replacing "It" with something more specific (e.g., "Government spending" or whatever is the case).
2. Conciseness is paramount in academic writing. See APA 3.08 (6th ed.) for a nice discussion and examples. I suggested changing to "reaching" for this reason.
3. I actually would prefer to change the end of the sentence to "cash dividends by 18%," but I left the idea of "substantially" there in case it was important for your context.
4. I'm blanking on APA's preferred style for expressing the monetary value, so I just followed Chicago style (16th ed., section 9.22) for now. You could also probably say "233 billion USD" without a problem, as long as you are consistent in your usage throughout the manuscript. Also, if you only use USD throughout the manuscript or the context is clear, the $ alone is sufficient and you can just say $233 billion.
As described by Grullon and Michaely (2002),
the legislation ofRule 10b-18 in the 1982of the Securities Exchange Act Release No. 19244 (November 17, 1982) gives USU.S. firms anexplicit guidelinespermission to buy back their shares without being afraid of being charged with manipulating their share prices.
Notes about these suggested changes:
1. I just quickly googled the rule and got the above SEC act but please double check because it's new to me. There might be other ways of referring to it. In APA, usually the preferred style is to refer to the law by name (for instance, if this law is commonly referred to as "the Safe Harbor Law of 1982" or whatever, then you could say that instead of using the cumbersome language I inserted there).
2. In APA, use U.S. (with periods) when the country is used as an adjective (APA 4.02), and use the full spelling or US (no periods) when used as a noun. If you are using Chicago style, revert back to "US" (no periods) for the adjective form per Chicago 10.33.
3. You could change "gives U.S. firms permission to" to "allows U.S. firms to" or something similar. There are several options.
4. If you want to stress the change that occurred with the passage of this rule, I suggest changing "gives" to "gave." if you want to focus on the present times and firms' continued ability to have a safe harbor, then the present tense is the better choice. This is a subtle but helpful tweak to help the sentence fit within the surrounding context.
5. "As described by" is okay, although it is rather bland and may or may not give too much prominence to the authors, depending on how authoritative their text is on this particular issue and how the introductory phrase fits in with the surrounding context. I have noticed that many authors rely too heavily on phrases such as "according to" and similar wording, so I just thought I'd mention it. If the phrase doesn't really add much meaning to your discussion and featuring the authors' names is not particularly important, consider using a more specific, relevant opening phrase to the sentence to create a better link to the surrounding text; then move the author-date citation into a parenthetical citation at the end of the sentence. Making this change throughout your intro and lit review will probably strengthen the writing, although again I'm taking a bit of a guess here.
Hope that was helpful and good luck! :)