That’s difficult to put an answer on! If we can gather enough information and evidence, then we can make a really good attempt at proving something through scientific analysis. I don’t know exactly how many things we can prove though – there are a lot of experiments going on all over the world!
Theoretically, science is a discipline for solving problems. It is therefore almost accurate to say that 100% of things can be proven by science. Almost everything is linked to science including criminal investigations and statistical analysis of data in all disciplines.