Where Did All The Ghosts Go?

A TV remake of the Enfield Hauntings of the 70's has led to a few conversations recently and more than a few retellings of ghost stories.
As i have never seen, smelt or encountered a ghost of any kind i do find the whole business of hauntings as a bit of a lark and if Scooby Doo has taught us anything, where there are a ghosts it always turns out to be a team of burglars or the creepy old caretaker.   

My question is where have all the ghosts gone because i remember back in my youth you couldn't swing a cat without hitting a poltergeist or some such smashing all the plates in the kitchen cupboard and levitating young teenage girls in their beds.
Considering that almost everyone has a mobile phone with a camera attached, you would have thought that if there were spirits and things hanging around with us, someone would have captured a convincing image by now but if anything ghost sightings have gone down.
I have heard it explained that housing and the proliferation of moulds that give-off gasses that could be mind altering was the cause. A persuasive argument that relates to the modernisation of dwellings and the war on damp and rot.
In the 70's and 80's films there was films such as Poltergeist and The Exorcist giving us the willies and more people put the picture falling off the wall down to malevolent spirits and less to their own dodgy DIY skills.
Likewise in the 90s, shows like the X-Files saw a spike in alien lights in the sky with the suspected consequence of hordes of anal-probe armed Martians scanning the Southern States of the USA to complete their interstellar trip.   
On that point, why is nobody is asking why is it Americans who seem to get anally probed by aliens more than most nationalities and why would an alien intelligence travel across the vast unimaginable expanses of space just to put something up a hillbilly's backside? 
It would appear that ghosts have gone the same way as the Loch Ness monster, demonic possessions and Jesus's face in toast and been left behind in the last century.