Since joining the European Union in 1986 Spain has seen membership act as an effective booster rocket for its economy, a key argument the "yes" camp is wielding ahead of a February 20 referendum on an EU constitution.

The Spanish vote will be the first of a series of make-or-break referendums in the 25-nation EU and the spectacular amount of ground that Spain has made up after almost 40 years of isolation under General Francisco Franco's military dictatorship is liable to bolster support.

According to Jose Antonio Herce, director of Spain's Foundation of Applied Economic Studies (FEDEA), EU membership has provided a "sustainable" boon.

For Nuria Bustamante, analyst with the Caja Madrid bank, Europe "has given a substantial push" to the economy and "propelled it into a virtuous circle."

The statistics would appear to bear that out.

Average per capita Spanish GDP on EU entry stood at just 68 percent of the average for the Union as a whole.

In the 18 years that followed it rose 18 percentage points as measured by the 15-member Union -- prior to last year's enlargement to 25 -- and now stands at 95 percent of the new average, most of the latest arrivals comprising former Eastern bloc states.

Last year, for the tenth year in a row, Spanish economic growth outstripped the EU average as GDP raced ahead 2.6 percent across 2004, according to a Bank of Spain estimate.

Unemployment, while still at the high end of the EU spectrum, has fallen from 20.6 percent of the active population in 1986 to 10.38 percent last year, which saw 461,300 new jobs created.

Spanish infrastructure has grown apace, the country now boasting 8,000 kilometres (5,000 miles) of motorways and highways criss-crossing the country, with official figures showing that EU development funds amounted to 40 percent of the cost of building them.

In all, Spain received more than 105 billion euros (81 billion euros at current rates) in EU aid between 1987 and 2003, according to official figures.

German Chancellor Gerhard Schroeder, his own country's economy struggling to live up to its traditional image of Europe's locomotive, felt obliged in 2003 to point out such largesse to former Spanish prime minister Jose Maria Aznar.

Aznar had earlier maintained that Spain's economic upturn was largely down to his government's policies.

Spanish economists believe that EU aid gives a fillip of between 0.4 and 0.5 percent to Spain's growth figures, translating into an annual bonus in terms of job creation of around 300,000.

With ten new states, and ten that are less well off than Spain, having joined the European Union last May, the flow of aid is bound to diminish in the coming years as the latest arrivals benefit from the solidarity of their partners.

"We have to accept we are no longer a poor country," notes Herce.

But the substantial aid that Spain has received cannot alone explain the increasingly blooming health of the economy, which in fact is also down to meticulous preparations undertaken ahead of the country's entry into the eurozone.

Spain, under eight years of Aznar, also rigorously applied the constraints of the EU Stability and Growth Pact, limiting public deficits to a maximum three percent of GDP and debt to 60 percent of GDP.

According to Finance Minister Pedro Solbes, Spain's public deficit at the end of last year was "well below" 0.8 percent of GDP, though the definitive figure is not yet available.

In the preceding three years, Spain had either registered a zero deficit or even a small surplus.

On public debt, the latest available figure for 2003 showed Spain well inside the ceiling at 50.7 percent of GDP.

Spain has not proved to be quite so successful at holding down inflation, which stood at 3.2 percent for 2004, while worker productivity lags the EU average.