Table: ken_schrader_stats
Columns: year
starts
wins
top_5
top_10
poles
avg_start
avg_finish
position

Question: WHAT IS THE LOWEST AVERAGE FINISH FOR 40TH POSITION, WITH A TOP 5 LARGER THAN 0?
SQL: SELECT MIN("avg_finish") FROM ken_schrader_stats WHERE "position" = '40th' AND "top_5" > 0