Although it's rare, with the odds of getting struck in your lifetime being roughly 1 in 12,000, every now and then a human will provide an attractive target for lightning bolts to unleash their power. And of the roughly 500 people who are struck by lightning each year, about 90 percent survive.
thin walls.
a moist inner surface.
a huge combined surface area.
I think the answer is 90%. According to the recent National institute of Health, Microbes in the human body estimates that 90% of the cells in human body are bacterial, fungal, or otherwise non-human. Despite the arguments that bacteria enjoys a commensal relationship with the humans hosts, only a fraction of the human microbia has been characterized.