If you're a grandparent, Sunday is all about you. Grandparents Day, established by federal proclamation 33 years ago, calls on America to honor a segment of the population whose responsibilities in the rearing of grandchildren and the joys in spoiling them grow each year.

Here are some Grandparents Day facts from the Census Bureau, AARP and the MetLife Mature Market Institute that may surprise you:

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About 65 million Americans -- 20 percent of the population -- are grandparents.

The majority of grandparents are baby boomers.

10 percent of all children in the United States live with a grandparent.

The median household income for grandparents responsible for grandchildren under the age of 18 is $45,000.

The average age of a person becoming a grandparent for the first time is 47.