Only 30 representatives passed on re-election bids in 2006 (less than 7% of the House), and 38 did so in 2010. On the other hand, while 1992 remains the record year for voluntary departures, the GOP gained just a net 10 seats from Democrats in that year's elections.
Near-record number of House members not seeking re-election in 2018 - April 2018
Numbers have changed slightly since then, and while this year may be extreme, it is also true that it may be within historical boundaries. Lots of variation, for all sorts of unrelated reasons.
I do think that a number of these are leaving because they think the "in house" gravy train is going to run out, so it's time to go through the revolving door.
To me, this observation is similar to the 50,000 sealed indictments (and if we keep accumulating them, we'll have a million of them in ten years). There might be a slight uptick, but if so it's been ongoing and systematic.
Indictment denier!
:)
Bagster