The blogger at Naturism as a Way of Living wondered how frequently people were searching for the term “naturist” as a function of time. Google Trends had the answer. The result:
Not very encouraging, is it? At least since 2004, searches for “naturist” have been decreasing over time – in spite of the rapid growth of the Web since then. This sort of parallels the decline in membership of the two U. S. national naturist organizations (TNS and AANR). At least the curve seems to have flattened out in the past 3 years.
What’s going on here? The data reflect searches not just from the U. S., but since “naturist” is an English language term, it’s fair to suppose that interest in the U. S. makes up the largest part of searches. It could be that there is an intrinsic decline in interest, due to factors that one could speculate on. However, it would also be fair to suppose that the national organizations, despite their efforts, are not doing an effective job of promoting naturism.
Naturist Philosopher 
http://www.google.com/trends/explore#q=nudism%2C%20naturism%2C%20nudist%2C%20naturist%2C%20FKK&cmpt=q
Expand the trend analysis to different terms and you may have a different story. Also check the regional report. Perhaps it’s the term “naturist” that has fallen out of favor more than interest in social nudity. And the USA is not in the top.