That's normal. The system is usually going to be responsible for a good portion of battery usage, because the phone needs the system to run.
If you think you're having abnormal battery drain, a couple of things to focus on would be:
1. Poor cell signal. You have only one bar in that screenshot, and your Phone Radio is using 12% of battery. Some of this may be due to having to strain to latch onto a weak signal, which can use more battery.
2. GPS can be a battery sucker--turn it off unless you absolutely need it. Change your Location Service to Battery Saving (which uses only wi-fi or cell signal to estimate your location).
3. NFC might use a bit of extra battery as well. If you never use it, turn it off.