Not sure if it still holds true, but there used to be much more software available for Windows based systems. With all the open source today that may not be as true. The other thing is I think for years the main target for hackers were Microsoft based systems. This may have been because they were more familiar with the code and there were more target to hack. A lot of people moved to some Linux based network systems because they seemed more secure. It’s not that often you hear of a flaw or bug in a kernel that is being exploited in Linux. It’s mainly Windows exploits.