This is a difficult question because it involves statistics of low numbers and many factors related with the way the impacts were found. Since we only observe one side of the planet this number results in a minimum flux of impacts of 1.4 per year but observations from the Earth concentrate on particular periods of time close to opposition and with good weather at the location of the different observers on Earth. In order to study the flux rate of impacts Marc Delcroix runs an statistical analysis of non-detections from the log files produced by the software DeTeCt in its different versions. You can find an updated estimation of the minimum flux rate of impacts in Jupiter on his impact analysis website.
The latest estimation on this website (as of August 2017) was 4.4 impacts per year but this may be a lower estimate since the analysis is based on the statistics of non detections over 71000 videos comprising a total of 2000 hours of observations by about 71 observers collaborating in this project.