Oh we do? Expert status achieved. Who had the under?
In reality, the vast majority of the Universe is hypothesized to be made of dark energy. A much smaller, but still quite large proportion of the Universe is thought to be composed of dark matter. And then there is a small chunk left of the matter that we can directly observe. It's not 96% of matter, but it makes up somewhere in the mid 80% of matter.
None of this has anything to do with string/superstring/M theory, though.
Go ahead and talk, Mr. Expert. Expert! Expert! Expert!
				
						