Nice graph breaking down voting by age group over time. I guess it is easier to get to the polls using a walker as opposed to a skateboard. Go figure...

Hard to see the colors, but the line in the middle (58.2% on the right) is the"Total Voting Age Population" trend line.  The top line (68.1%) represents "65 years and over". The other age groups are above or below the Total Voting Age Population line.

If you follow the 65 years and over line from right to left, you will see it is pretty steady over time. 
While there is a decline in every other age group along the way, they show back up in the golden years.

If you were running for national office, which group would you target for votes and which group would you pay lip service to?   Yeah, me too. 

Source: Conversable Economist