What is the proportion of the strength signals between wired and wireless mouse/keyboard?
There's orders of magnitude difference in the signal strength. Although virtually every electronic thing radiates some RF energy, most don't radiate much at all unless they're designed to. There's two reasons for this.  

1) Making electronics radiate RF effectively usually requires you to have a resonant setup. There's an entire field of electrical engineering just dealing with antenna design to come up with effective ways to resonate electrical signals to allow them to effectively convert the energy into RF. The wireless mouse/keyboard have an antenna specifically designed to convert electricity into RF.  

2) Most electronics that could resonate easily creating unwanted RF are purposely designed or changed to not emit RF easily. The FCC states that electronics must not cause unwanted interference so designers have to ensure they don't do so. One example of engineers lowering the amount of RF noise is with CPU clocking. Instead of clocking at the same frequency constantly creating an RF noise spike, they perform spread spectrum clocking so the noise is distributed over a wider bandwidth and is therefore lower at any given frequency.