Thousands of Scots claimed they were "too busy" to complete the 2022 census, an SNP minister has revealed.
Angus Robertson told MSPs the most common excuse among people who failed to fill in the £150m national survey was they did not have enough time.
Completing the census - which is held once every decade - is a legal responsibility but more than 10 per cent of Scots did not bother.
The National Records of Scotland (NRS) set a national return rate of 94 per cent - but the final total was just 87.9 per cent despite the May 1 deadline being extended.
The rest of the UK carried out a census last year but SNP ministers chose to delay the Scottish equivalent due to the pandemic.
The return rate south of the Border stands at 97 per cent - almost 10 per cent higher than in Scotland.
Late returns from Scots are being accepted until June 12.
The Conservatives today claimed the census "lies in ruins" as a result.
Robertson insisted lessons would be learned from carrying out this year's survey.
"It is important that we understand why this happened so that lessons can be learned for the future of the census," he said.
"While many reasons were offered by householders by far the most common at 35 percent was “too busy.”
He added: “We extended the collection period to ensure that as many people as possible could have the opportunity to complete it.
"Since the start of the extension, we have seen significant progress with 10 local authorities achieving a return rate of more than 90 per cent and 28 local authorities having a return rate of more than 85 per cent.
"This data will provide us with a strong position as we move to the next phase and turn this data into actions that will benefit people across Scotland."
Tory MSP Donald Cameron said: "The Scottish return rate is almost 10 per cent behind the return rate of the rest of the UK.
"Glasgow, our most densely populated city, is a write-off at 81 per cent.
"We have had delay after delay after delay and an ever increasing bill for taxpayers."
Cameron added: "We were told a few weeks ago that Scotland's census had solid foundations - but Scotland's census lies in ruins.
"It is a disgrace. The SNP could have run the census in sync with the rest of the UK last year, but, as always, it had to be different and the cost of that decision is plain for all to see."
Labour MSP Sarah Boyack said: "When the SNP decided to delay the census by a year they said it was ‘the only option in which there is confidence of producing high quality outputs and deliver the benefits by the people of Scotland’.
"The facts speak for themselves – this whole process has been a catastrophe of the SNP’s own making.
"The Minister can blame people for being ‘too busy’ all he likes but it does not hide the fact that he has been posted missing at a crucial time.
"All the SNP want to do is devolve responsibility for failure to the people of Scotland and reserve the right to avoid criticism."
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