during the baby boom the u.s. experienced after world war ii, the dramatic rise in births led to a higher dependency ratio, which means that there is a large portion of the population under the age of 15 and over the age of 65 that relies on those in the work force (ages 15–64). the cohort of this baby boom is expected to once again increase the dependency ratio once the majority is over the age of 65, as these people will no longer be part of the work force. some of the 75 million baby boomers began to reach retirement age in 2011. in the year 2000, only 12.4% of the population was 65 or over and is predicted to rise to 18% by 2020, largely due to the baby boom. currently the government supports social security to the population over 65, which may lead the states increasing their budget to fund programs like medicaid.