Some historic perspective on growth in US Amateur Radio:

Numbers of US population, the number of US hams, growth over the
previous decade and ratio of hams to population at the start of each
decade from 1930. Thanks to W5ESE for the pre-2010 info. (# of hams is
of individuals and does not include grace-period licenses)

Year Population Hams Growth Ratio
1930 123,202,624 19,000 6,484 to 1
1940 132,164,569 56,000 +194% 2,361 to 1
1950 151,325,798 87,000 +55% 1,739 to 1
1960 179,323,175 230,000 +164% 780 to 1
1970 203,211,926 263,918 +15% 770 to 1
1980 226,545,805 393,353 +49% 576 to 1
1990 248,709,873 502,677 +28% 495 to 1
2000 281,421,906 682,240 +36% 412 to 1
2010 309,026,303 688,326 +4.5% 449 to 1

(hopefully that will stay formatted)

Note that the decade of greatest percentage growth was the 1930s.

Until 2000, the decade of least percentage growth was the 1960s.

73 de Jim, N2EY