Don't be too swayed by percentages, because screen time is almost always going to take up the most battery, and as such, will usually be the highest on the list of percentage use. This can actually be better than seeing Android OS or other processes at the top of the list, because that sometimes means there's some runaway process that's actually using a greater percentage of battery than the screen.
What's more important is how much battery life are you getting before you have to charge? Keep in mind that since screen usually uses the most battery, a reasonable amount of total screen-on time is anywhere from 4 to 6 hours, depending on the device and your usage pattern. Post your battery stats when you're battery's mostly discharged, and we'll see how that looks.
In the meantime, review this guide, if you haven't already:
http://forums.androidcentral.com/gen...ving-tips.html