Which year earlier than 2006 has the average Total Convictions of Fraud at 1,521?
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
)
SELECT AVG("Total Convictions") FROM table_6170 WHERE "Fraud (Art. 146 StGB)" = '1,521' AND "Year" < '2006'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: Which year earlier than 2006 has the average Total Convictions of Fraud at 1,521? ### Input: 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
) ### Response: SELECT AVG("Total Convictions") FROM table_6170 WHERE "Fraud (Art. 146 StGB)" = '1,521' AND "Year" < '2006'