Debt ratio to disposable income

Hi,
The press quote statistics regularly about Irelands personal debt being very high. The statistic quoted is household debt ratio to disposable income.

I would be very interested in knowing the detail sof how this is calculated.

What is the definition of disposable income used in this calculation ?
I assume household debt is the debt owed by the household but is martgage included.

Can anyone point me to a primer on this issue ?

Thanks