Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_6170 ( "Year" real, "Total Convictions" real, "Homicide (Art. 111,112,113,116 StGB)" real, "Serious Bodily Injury (Art. 122 StGB)" real, "Minor Bodily Injury (Art. 123 StGB)" real, "Sexual Contact with Children (Art. 187 StGB)" real, "Rape (Art. 190 StGB)" real, "Theft (Art. 139 StGB)" real, "Robbery (Art. 140 StGB)" real, "Receiving Stolen Goods (Art. 160 StGB)" real, "Embezzlement (Art. 138 StGB)" real, "Fraud (Art. 146 StGB)" real, "Narcotics Possession" real, "Major Violation of Traffic Laws (Art. 90 SVG)" real, "Drunk Driving (Art. 91 Abs. 1 Satz 2 SVG)" real )

### Question ###
Which year earlier than 2006 has the average Total Convictions of Fraud at 1,521?

### Accurate SQL ###

SELECT AVG("Total Convictions") FROM table_6170 WHERE "Fraud (Art. 146 StGB)" = '1,521' AND "Year" < '2006'