According to a recent report, in 2013,

... the maximum annual contribution to a Health Saving Account (HSA ) was $3,250 for account owners with individual coverage and $6,450 for account owners with family coverage; persons who had reached age 55 and not yet enrolled in Medicare could make an additional $1,000 catch-up contribution

• Overall, 15% of all accounts received the maximum contribution
• 16% of accounts belonging to men received the maximum contribution
• 10% of accounts belonging to women received the maximum contribution

Source: "Who Maxes Out on Health Savings Accounts," Employee Benefit Research Institute (EBRI) Press Release, January 29, 2015, http://www.ebri.org/pdf/PR1109.HSA-max.29Jan15.pdf