TRAC's FOIA Project has this on the incredible increase of FOIA lawsuits in fiscal year 2017 - which covers approximately 2/3 of the current administration's first year. During 2017, FOIA lawsuits numbered 651 up from 515 from FY 2016. Agencies such as Justice, Interior and EPA had large increases in the number of lawsuits filed against them.
While I don't expect the rate of the number of lawsuits to increase in FY 2018, I believe they will trend near the 2017 level for two reasons - 1.) political issues arising out of various agencies and the lack of transparency on those issues and 2.) increased delays in responding to FOIA requests because of the administration's failure to fund and operate FOIA Operations adequately.