Is data on population size of congressional districts available for 1972-2012? Or at all, by interpolation?

I need the population, or 18-years and older/VAP, population for each congressional district for even years from 1972-2012.

My understanding is that the data are available in decennial congressional district files available for 1990, 2000 and 2010. But I cannot find an online tool that would allow me to download the data without going by district (435!) for those years.

Is anything better available?

The NHGIS project, housed in the Minnesota Population Center , offers many of the Census summary tables at the Congressional district level as far back as 1967. While NHGIS is primarily focused on mapping data, the summary tables can be extracted independent of shape files as .csv files with optional descriptive headers. In your case, you can create one .csv file for each decennial census year from 1970-2010 with the population of each Congressional District broken down by age within each file.

Hope this helps.