I guess I have a different list of criteria about caring. The presumption with what's posted, seems to be whether she is a girlfriend or not. or if you are jaded, whether she can make money off you or not.
but what about:
1. she chats you up, even though she knows you are a couple thousand miles apart and there is no way she is getting a visit out of you?
2. she helps you find a girl, when you go to another town, or even better, she steers you away from a shop, or a girl that she knows is no good?
3. you can call her up when you need help with a chinese translation, and she skips a rotation to get on a call and help you out?
4.she's retired, but invites you to stay with her, cooks for you, and willing to do it just for fun?
5. she hounds you about diet, physical maladies every day?
these are all things that have happened to me. iIts not because I am something special. Its because I treat them like friends (in a complicated way) from the very start, am honest to them. And i reiterate/initiate in kind for them when they ask. In other words it can be like any other friendship.
As to the percentage, thats a crass question. But I have more than 10 spa girls who i have been in contact with for over 10 years now like this.