Windows 10: NT Kernel consistenty taking 25% of CPU Usage

For about 3 weeks I have noticed that the system process in windows 10 is taking 30% of my cpu. I have searched the web and found various ideas for addressing the problem but my techncal skills are a little rusty. I have attached a screenshot from windows performance analyser and wdered if there was anyone who could suggest what I should do next.

Here's hoping.

Isolate the programs, start-up programs, services and scheduled tasks that causes that CPU usage

Thanks for the advice but I don't know how to do that. If I use Task Manager it tells me that the Process: System is using ca 30% consistently, if I then look at the details I can see:

Process Name: System
PID: 4
Status: Running
Username: SYSTEM
CPU: 25
Memory: 24K
Description: NT Kernel and System

I cannot stop the process