1996

2000

2004

2008

2012

2016

By actual election results

Mean victory margin

16.3

21.7

21.5

19.8

18.3

20.6

Percentage of competitive districts

17.7

9.7

5.1

11.5

14.0

7.4

Percentage of safe districts

65.3

78.2

83.0

72.9

67.4

75.4

By the district normalized presidential vote

Mean victory margin

10.0

11.2

11.6

12.0

13.3

14.7

Percentage of competitive districts

30.6

28.0

25.1

25.5

19.3

15.6

Percentage of safe districts

39.5

45.3

48.0

49.9

57.5

61.8