Total Number of Incumbents Seeking Reelection and Number of Open Seat Districts

2000

1998

1996

1994

1992

1990

1988

No. of Incumbents

408

407

389

393

371

409

413

No. of Open Seats

32

33

51

47

75

30

27

(The number of incumbents plus open seats does not always equal the total number of districts because some districts had two incumbents running in 1992.)