Scientists estimate that they have mapped 0.42 percent of the observable night time sky as of 2015, but they have no way of determining what percentage of the entire universe the observable portion comprises. They hope to map 12.5 percent of the observable portion by 2018.
Confounding scientific efforts to map the universe are theories that hold the universe is either infinite or constantly expanding at various rates. Recent observations indicate that the rate of expansion is slowing at times and expanding faster than the speed of light at others.
Another problem concerns the existence of dark matter, which makes up as much as 98 percent of the universe according to some estimates. Scientists do not understand the composition or behavior of dark matter. Einstein hypothesized that some areas of space have the capacity to produce more space. If this is true, it makes determining the percentage of the mapped universe impossible to state with any degree of accuracy.