The percentage of full-time residents will vary according to the resort.....however it is pretty low. It really depends on the type of property available on the particular resort. Most UK purchasers (who form the majority of PW resorts purchasers) are not used to apartment living and so dont really purchase apartments for 'retirement' living. Most would only consider retiring into a villa....although not all.
Mar Menor is all villas so probably has a higher number of 'permanent' residents than HR will ever have. However it is still a low percentage...about 15 % would be a reasonable guess..so MM has about 700 villa properies so probably around 100 permanent. La Torre has many more mixed properties but is a bit of a ghost town outside UK school holidays...again you will be lucky if there are more than 100 permanent if that. EV the same was deserted last time I was there so really dont know about that one.
Difficult to assess HR....but again it is unlikely that there will be anything other than a very low percentage of permanent residents.It is probably true to say that these numbers should increase a little over time as people buying now are probably planning retirement somewhere down the line, but HR, being all aprtments, does seem to be the resort where most have bought primarily as rental or investment properties or just a holiday place for a few weeks a year in the UK hols.