There are none, I believe; it comes down to individual servers.
Like Mesarthim, DE, which is with Contabo.
Meissa, LV, is with DataClub.
Sheliak, NL, is with Global Layer.
You can check them with IP APIs, like ip-api.com's isp and as properties in the response.
$ ip-api sheliak.airservers.org
{
"country" : "Netherlands",
"regionName" : "South Holland",
"city" : "Alblasserdam",
"zip" : "",
"lat" : 51.8703,
"lon" : 4.6702,
"timezone" : "Europe/Amsterdam",
"isp" : "Global Layer network",
"org" : "AirVPN.org entry server (Sheliak)",
"as" : "AS49453 Global Layer B.V.",
"mobile" : false,
"proxy" : true,
"hosting" : true,
"query" : "213.152.186.34"
.