Where to find historical dream activity data? Is it just me, or are we dreaming less? Maybe it's the computer screens in our face all day. Maybe that's just what happens when we get older.

I'm wondering if there's a resource of some kind to determine historical dream activity. Might it be possible to use Google Trends to determine dream activity (similar to how Google Flu tracks illness via search queries). 

Or is Google too novel a tool, and are dreamers searching too randomly to track any meaningful delta in dream activity? If so, is there another resource that might provide meaningful dream data?
I think you need to distinguish dream activity and dream recall. I thought that everyone dreams every night. However, many factors influence whether we recall the dreams. 

Thus, I think a more productive search would be to focus on the factors that influence dream recall, and perhaps the prominence of dreams in peoples lives.

I found one older article by Cohen (1973) which summarises research on the frequency of dream recall. He states that 


  Frequency of dream recall is affected by physiological, methodological, and psychological factors. 


Beaulieu-Prevost and Zadra (2005) writes


  Schonbar (1965) suggested that people who remember many dreams are
  generally interested in dreams, in trying to understand them, in
  increasing their dream recall frequency, and tend to have an overall
  positive attitude towards dreams.


Beaulieu-Prevost and Zadra (2005) then go on to cite numerous such studies.

Thus, the next question would be whether the factors that influence dream recall have changed over recent history.  Palagini et al (2011) might provide a useful starting point as they review historical perspectives of dreaming.

References


Beaulieu-Prévost, D., &amp; Zadra, A. (2005). Dream recall frequency and attitude towards dreams: a reinterpretation of the relation. Personality and individual differences, 38(4), 919-927.
Cohen, D. B. (1969). Frequency of dream recall estimated by three methods and related to defense preference and anxiety. Journal of Consulting and Clinical Psychology, 33(6), 661.
Palagini, L., &amp; Rosenlicht, N. (2011). Sleep, dreaming, and mental health: A review of historical and neurobiological perspectives. Sleep medicine reviews, 15(3), 179-186.