The median net worth for householders 65 and older dropped by 13 percent in the five years between 2005 and 2010, according to the U.S. Census Bureau.

In 2010 the median net worth was $170,128, compared with $195,890 five years earlier. The Census Bureau released a number of statistics about the group of people age 65 and older in conjunction with Older Americans Month in May.

The median income for householders 65 and older did not change substantially from 2010 to 2011. In 2011 it was $33,118. Likewise, the percent of seniors living in poverty did not change substantially between those two years and remained at 8.7 percent, or 3.6 million seniors, in 2011.

The number of older people in the United States and across the world is increasing rapidly, according to the Census Bureau. The number of people in the United States 65 and older on July 1, 2011, was 41.4 million, up from 40.3 million a little over a year earlier on Census Day 2010. That number is projected to more than double to 92 million by 2060, or just over one in five of U.S. residents. At that point 18.2 million will be 85 or older.

In 2060, the Census Bureau expects that 2.4 million baby boomers will be left alive, with the youngest ones being 96 years old. Four years before that, the U.S. population 65 and older will outnumber people younger than 18 for the first time.

Today, 8 percent of the world’s population is 65 or older. By 2050, it will be 17 percent. Europe has already tipped the balance between those over 65 and those younger than 15, the first region to do so. By 2050, Europe will be joined by Canada and the United States, Asia, Latin America and the Caribbean, and Australia and New Zealand.

The percentage of seniors who are continuing to work after 65 is increasing, at the same time studies are showing people are delaying retiring because they want to stay active or need the extra income. The percentage of seniors in the labor force in 2010 was 16.1 percent, up 4 percentage points from 10 years earlier. That translated into 6.5 million people in 2010 compared to 3.8 million in 1990. The percentage continued to increase in 2011 to 16.2 percent.

Alaska topped the states with the highest senior citizen population still working with 22.3 percent. West Virginia was the lowest with 12.5 percent of its seniors working in 2011.

In 2010, there were 53,364 people in the United States 100 years old or older. For every 100 women in this group, there were 20.7 men. North Dakota has the most 100-year-olds per 10,000 population with 3.29. It is the only state with more than three centenarians per 10,000 population.

Florida has the highest percentage of seniors, with 17.6, and Sumter County in Florida has the highest percentage of any county in the United States with 45.5 percent.