The overall number of people arrested on corruption charges dropped between 2014 and 2015 from 2,743 to 2,442.
But last year's figures are still more than six times higher than in 2010 - and mean than nearly seven Spaniards were arrested for corruption for each day of 2015. About 1,100 corruption cases are still ongoing.
Number of arrests for corruption
From the Spanish Interior Ministry report.
Over the past three years, more than 7,000 people have been slapped with handcuffs over corruption allegations.
The Spanish Government “has been forceful and determined to fight against corruption in our country over the past legislature,” Interior Minister Jorge Fernández Díaz wrote in the report.
The type of corruption that most commonly goes unnoticed is social security fraud (16.3 percent of cases), according to the report, followed by public finance fraud (8.1 percent).
Bribery made up 12.5 percent of corruption cases and embezzlement made up 8.2 percent.
The National Police and Guardia Civil investigated 6,488 businesses last year, finding 2,057 of them to have evidence of violations, including 847 fictitious companies.
They also investigated nearly 11,500 workplaces for labour violations, of which 4,616 were suspected of violating the Law of Foreigners.
In total, the report stated that fraud cases added up to nearly €80 million.
The interior ministry also reported that 445 groups and 18,463 people were investigated for organized crime last year. More than 60 percent of the groups were “totally dismantled”.
A number of high-profile corruption and fraud cases are ongoing in Spain now, including the trial of the king's sister, Princess Cristina, who is accused of tax evasion over her husband's business dealings.
The conservative Popular Party of Prime Minister Mariano Rajoy has faced a series of corruption probes, including a raid last week of the headquarters. Madrid party leader Esperanza Aguirre resigned in the wake of the raids.
Executives of a prominent chain of dental offices that serves millions of patients also fell into hot water this week when they were arrested over money laundering and tax fraud.
A report last month concluded that Spain was one of the most corrupt countries in the European Union.