The question to ask is "is that a lot?"
According to the statistical report I downloaded (NHS Wales Statistics 2016) there are over 900,000 visits just to A&E every year in Wales. So that means around two out of every hundred visits to A&E result in a physical assault (and that assumes all the 18,000 are in A&E, there are also around a million other treatments, each of which can have more than one visit). That doesn't strike me as a big number (obviously it is big compared with zero, which is the ideal).
Furthermore, Vlad's story has a table showing the history of assaults over five years for some areas. In only one case was the 2015-16 figure the highest. That suggests we could be on an improving trend. As secularism increases, hospital assaults decrease.