sentences:  Globally, acne affects approximately 650 million people, or about 9.4% of the population, as of 2010.It affects nearly 90% of people in Western societies during their teenage years, but can occur before adolescence and may persist into adulthood.While acne that first develops between the ages of 21 and 25 is uncommon, it affects 54% of women and 40% of men older than 25 years of age and has a lifetime prevalence of 85%.