If you only have IP addresses there are a couple of things you can do:
1) Work out who the IP address is assigned to. In the case of 188.8.131.52 it is Telefonica de Espana SAU so my guess is someone is using a Spanish ISP to look at your site.
You can find this info from here:
click here - just type in the IP address.
2) You can see if the IP address translates to a website by typing click here address so PC Advisor would be click here