The findings come from the 2015 Scottish Household Survey, which shows the overall number of homes in Scotland increased from 2.19 million in 1999 to 2.43 million last year – a rise of 11 per cent.
The latest figures show 14 per cent of all properties were leased from a private landlord, family member, friend or employer in 2015. This compares to five per cent in 1999.
The number owner-occupiers was the same as in 1999 at 61 per cent – down from a high of 66 per cent in 2009.
The proportion of the population staying in council or housing association properties has fallen, dropping from 32 per cent to 23 per cent over the past 16 years.
The poll found more than two-fifths of private renters had been in their home for less than a year, while more than half expected to move within five years.
Housing charity Shelter Scotland said the research is “further confirmation” that continued reforms are needed in the private rental sector to make it “more modern, stable, flexible and fairer for everyone that calls it home”.
Spokesman Adam Lang said: “Private renting in Scotland has tripled since 1999 with 350,000 households calling the sector home – including 91,000 with children.
“This growth along with major changes to the type of people now renting privately meant reform of the sector was vital.
“Shelter Scotland has been spearheading the push for reform to bring greater protection and increased security and fairness for tenants.
“Progressive and far-reaching changes in the laws on private renting –such as the new private tenancy – are a big step forward and will have a profound impact on how the sector is run.
“The challenge now is to enforce the legislation and to see that poorly performing landlords are supported to improve their practice and the worst landlords are removed from the sector.”
The proportion of Scots who cope well financially increased in the past year, although almost a quarter of single-parent families and 17 per cent of single adults said they do not.
The number of folk with over £1,000 has risen to 55 per cent, up 43 per cent from 1999 levels.
However, around half of residents in the social rented sector reported having no savings. This contrasts with a third of private tenants and less than one in ten owner-occupiers.