On the basis of a 5 points scale (very large, rather large, no opinion, rather small and very small) an index has been constructed, adding the percentage of Rs that answer “very and rather large”, subtracting from it the percentages that answer “rather and very small”, and adding 100 to standardize the result. The index may therefore vary between 0 and 200, so that the value 100 means that the proportion of individuals who think that the degree of corruption is very or rather large is equal to the proportion who think that it is rather or very small. Thus, it may be seen that Spaniards perceive a great increase in corruption since March 2003 to September 2009. Using the same index, data show that Spaniards believe that the greatest degree of corruption is found in local governments, construction and political parties (indexes higher than160) and the smallest is found in agriculture and the military (indexes lower than 80).