Of the Senate’s three oldest members, two — 84-year-old Dianne Feinstein of California and 83-year-old Orrin G. Hatch of Utah — are facing re-election races next year, along with four other members of the silent generation.

The average age in the current Senate is 62, while the average age in the House is 58. Here’s a look at how the age at election has slowly increased over the years:

Though recent reports suggest Hatch is leaning toward retirement, Feinstein has announced she is running for a fifth full term in 2018. And none of the other silent generation members have formally announced an intention to retire next year.

The senators who are leaving — 65-year-old Bob Corker and 54-year-old Jeff Flake — are two of the 23 baby boomers whose seats are up in 2018. Only one member of the silent generation, Florida’s Ben Nelson, is facing a competitive race. Eleven of the 12 races next year rated as competitive by Inside Elections with Nathan L. Gonzales are held by baby boomers.

Here’s a look at the generational makeup of recent Congresses: