The number of workers who participated in workplace retirement plans dropped slightly in 2012 to 39.4 percent, or 61.6 million Americans. But among full-time, full-year wage and salary workers, 53.5 percent participated.

According to the Employee Benefit Research Institute, the individuals who were least likely to participate in an employer-based plan were non-white, young, female, never married, those having a lower educational attainment, lower earnings, poor health, no health insurance, those working part-time or those working in farming, fisheries or forestry occupations.

Those working for smaller firms, private-sector firms or firms in the “other” services category were also less likely to participate in a plan than their comparison groups.

Where people live also had an impact on participation rates. EBRI found that workers in the South and the West were less likely to participate in a retirement plan than those in other regions of the country.

More men than women participated in plans. EBRI found that the gender gap closed quite a bit from 1987 through 2009, but began to widen again from 2010 to 2012. When EBRI controlled for work status or earnings, however, female participation rates actually surpassed those of men.

Non-native Hispanics had very low levels of participation compared to those born and raised in the United Staets, which brought the participation rate for Hispanics as a whole down. Black and native-born Hispanic workers had participation levels much closer to those of white workers within each age group, the report found.

Participation rates seem to rise or fall depending on how the stock market is doing. During the economic downturn, participation rates declined in workplace retirement plans. The market stabilized between 2010 and 2012. EBRI believes 2013 participation numbers will be very similar to 2012, maybe even slightly higher.