Bureau of Labor has calculated days of worked missed due to absence of workers for various reasons. The breakdown can be accessed here. The data show federal government workers miss more time than private sector workers.
In 2015, according to BLS, 3.8 percent of federal government workers reported being absent from work in the typical reference week compared to 2.7 percent of private-sector workers. Thus, a government worker was 41 percent more likely to be absent than a private-sector worker.