The House of Commons library data puts the UK behind 13 neighbouring countries, including Ireland, Norway, Sweden, Finland Denmark, Belgium, the Netherlands, Iceland, Switzerland, Luxembourg, Austria, France and Germany.
According to the research, which uses figures from the International Monetary Fund (IMF), the 13 countries produce more gross domestic product per person than the UK, and have done for the past 21 years.
Existing figures put the UK’s GDP per capita at £31,038 per person in 2021, placing it at the bottom of the league, behind France on £32,622 per head, and Finland which has a rate of £34,187.
Top of the league was Luxembourg at more than £80,000 per person, followed by Ireland at £65,411 and Switzerland on £50,015.
However, the research admits including Luxembourg, which has a small population but is a hub of private banking and investment, could skew the figures.
The figures also show the gap between the UK and its European neighbours has widened over the past two decades, from being 7.6 per cent or £2,219 lower on average to 16.3 per cent, or £5,062, lower on average this year.
For countries with a population of five million or less, the difference has gone from being 26.6 per cent lower than average in 2000 to 50.7 per cent lower this year.
SNP deputy Westminster leader Kirsten Oswald said the research backed her party’s desire for independence as it illustrated that countries which are smaller than, or of the same size as, Scotland "do better".
She said: “The UK is now a whopping £15,739 per person less wealthy than those independent European countries similar in size or smaller than Scotland."
A UK Government spokeswoman said: “Our economy is one of the strongest in the world, in large part thanks the strength or our Union.
“Scotland continues to benefit from the £352 billion package of coronavirus support, which is one of the most generous in the world and has protected one in three Scottish jobs and more than 90,000 businesses.
“And next year Scotland stands to benefit from over £100bn in capital investment across the UK, including investment in green energy and jobs for people in Scotland.”