There’s some interesting reading in a new Congressional Research Service report (PDF), including a breakdown of the male-female split of who is serving in Congress:
Catherine Rampell notes that military service among representatives and senators has declined:
Having experience in military service peaked in both the House and the Senate in the 92nd Congress, which served in 1971-72. In that session, about three-quarters of legislators from each house had served. Member military service has fallen since then — but then, so has that for the nation over all.