Are there any resources where one can view the popularity of a move by year? I am currently under the impression that White players are allowing the Nimzo-Indian more and more, whereas before they were dodging it via 3. Nf3.
I wanted to check if that is true, but usually databases do not contain this information explicitly. Are there any resources (software or websites) that have this feature?
SCID's Opening Report shows some statistics which may be useful here. From a given position, one of the things it does is generate a table which shows what moves are common from a given position:
4.2 Moves from the report position
    Move   ECO       Frequency    Score  AvElo Perf AvYear %Draws
 1: Nf3    E10a     8561: 50.8%   56.1%  2622  2665  2009   56%
 2: Nc3    E00d     6495: 38.5%   55.6%  2607  2654  2008   54%

The &quot;AvYear&quot; column there shows the average year in which the move was played.
And another table looks like this:
1.4 Current popularity

Year               1800-99 1900-49 1950-69 1970-79 1980-89 1990-99 2000-09
Once every X games   ---     24      19      13       6      33      12   

Frequency in all years:   once every 12 games
In the 10 years to today: once every 13 games (down 7% from all years)
In the  5 years to today: once every 12 games (no change from all years)
In the  1 year  to today: once every 0 games (no change from all years)

which seems like it would be useful.