A current report from AmeriCorps estimates the rates of volunteerism between generations:
• Generation X: (ages 45 to 56)
36.4% — 21,720,574
• Baby Boomers: (age 57 to 75)
30.7% — 22,631,756
• Millennials: (age 26 or so to 44)
28.2% — 19,904,598
• Generation Y:
26.1% — 6,456,628
• Silent Generation: (over age 75)
24.8% — 6,673,509
Further, 30.0% of veterans volunteer, and 39.9% of parents volunteer.
One frustration we encountered when considering the AmeriCorps figures is the suggestion that Generation Y and Millennials are two different groups, while many demographers use the terms synonymously. The figures above infer that these two generations span more than 95 million Americans, which is inconsistent with other published definitions. The US Census Bureau is little help, as they only seem to define Baby Boomers and those who are older or younger.
(Source: AmeriCorps: Volunteering in America: Demographics)
https://americorps.gov/newsroom/news/via AmeriCorps.gov