* The percentage of people who *don't* get an education? This would depend heavily on what you define as "an education" (primary school? secondary school? some form of higher education?). Globally, a significant portion of the population lacks access to even basic education, but the exact percentage varies wildly by region and definition.
* The percentage of people who get an education, but don't complete it? Again, this depends on what level of education you're considering. Many people start primary school but don't finish, and similarly for secondary school and beyond. Dropout rates are a commonly tracked statistic but vary substantially by country and socioeconomic factors.
* Something else? Please clarify your question.