The data needs cleaning (and every small edit or redirect helps), but
multiple sources agree on a trend similar to this, from 2011 to 2014
(partial): 943, 778, 489, 250.
http://wikipapers.referata.com/wiki/2011
http://wikipapers.referata.com/wiki/2012
http://wikipapers.referata.com/wiki/2013
http://wikipapers.referata.com/wiki/2014
What's going on?
Nemo