Telles' second system is that of popular classification. Two IBGE surveys made more than 20 years apart (the 1976 National Household Sample Survey (PNAD) and the July 1998 Monthly Employment Survey (PME) have been analyzed to assess how Brazilians think of themselves in racial terms. The IBGE thought the data might be used to adjust classifications on the census (neither survey, however, resulted in changes to the Census classifications). Data Folha has also conducted research on this subject. The results of these surveys are somewhat varied, but seem to coincide in some fundamental aspects. First, a great number of racial terms are in use in Brazil, indicating a flexibility in thinking about the topic. The 1976 PNAD found that people responded with a total of 136 different terms to the question about race; the July 1998 PME found 143. However, most of these terms are used by small numbers of people. Telles notes that 95% of the population used one of 6 different terms for people of color and at least some African ancestry ("branco, moreno, pardo, moreno-claro, preto" and "negro"). Petruccelli shows that the 7 most common responses (the above plus "amarela") sum up 97% of responses, and the 10 most common (the previous plus "mulata", "clara", and "morena-escura" - dark brunette) make 99%.