Over the internet it is quite high because you can easily hide behind a fake ID and fake address. Not to mention that most of the Facebook and social media IDs of girls for this purpose are created by guys. Almost 90%.
I’m not saying that 90% Facebook and social media profiles of girls are fake, but if you go to some ‘colorful’ desi groups/pages that are created for such purposes, majority of the female profiles are fake and to top it all majority of them claim to be lesbians and university students… 
So a new person who goes to such pages/groups automatically assumes that majority of university girls are into this stuff and are potentially easy lay.
Still in real world, the %age of the ‘real act’ is not more than 15% to 20%. That’s my experience, may be others have seen more than what I have.
The bad side is that the parents have children reaching the age of 30 and still they do not consider how their adult son or daughter is able to live in today’s world without thinking about intimacy or love. It’s a basic human need and every religion and society has provided a legal way to satisfy it.
Many people here said about high percentage among university students so we can assume people in age bracket of 22-25 are more susceptible to the actual act. The question is why they have to look for illegal means to satisfy their needs? We cannot claim them to be isolated cases, in Pakistan even a 10% means 18 to 20 million people and they are not in their teens to not know they are taking a wrong path.
We look around in the west where every John and Jane work hard/study and also have intimate relationships. Sometimes the things do go wrong and they breakup and move on to find next partner but they don’t hold back their desire and needs. It leads to psychological disorders, double personalities and creative and sick ways to fulfil these desires as well.
An example of creative way is the lists of mobile numbers of females sold by shopkeepers. The idea is simple, the females go to a shop to recharge their prepaid mobile phones, they have to tell their number to the shopkeeper for the topup. The shopkeeper will note down the number as well as details of the female, like her approx. age, color, appearance, religious looking or fashionable etc. Later he will sell the number and the details to the guys who are willing to pay.
I went to Pakistan last year and saw this happening, the youth will be willing to pay the money and get the numbers. Later these numbers end up in friends circle and also on Facebook pages, if the girl gave strict answer to the “fraandship offer”. When the news spreads in the neighbourhood then whole youth of that area assumes that girl is an easy lay.
Of course there are girls as well who get excited by all this attention and respond positively to such cheap acts. Her whole life has been empty so far and now a ‘*mushtanda’ *is giving her attention and waiting for her on his 70cc bike or dad’s Rolla (I mean Corolla). One success story in 100s gives encouragement to many people to keep on trying.
I have countless examples of girls/guys who are over 30, unmarried and parents (and children as well) waiting for some ‘good’ rishta. Okay finding good rishta is very important but do they ever think that how their daughter is able to hold back her desires this long. The same goes for guys as well, I don’t want to be gender specific. The religion is one possible way (may be) but majority of us are not religious at all in any aspect of life.
The point is society and parents want their children to live the pious, sinless and honourable life without realizing that humans are not able to live such life for such a long time, esp. when there are enough opportunities around.
Encouraging and helping children to find their potential partners, early in their life, is the right way to go. There was a quote floating on the Internet that "make nikkah easy and zinnah difficult".
This should not be specific to the expenses related to the weddings but also opening up your mind (encouraging your children to find their life partners and not friendships just for time pass), decision making (if you find good rishta as parents, involve your children in the decision making process), accepting the mistake/failure (if marriage doesn’t workout so what) and then moving on (change in the society to accept divorced girls/guys and marry them without creating a fuss over it).
Now I don’t know why I wrote this long post, but I wrote it anyway… you may not agree with me but that’s okay.