Table: nascar_driver_stats_2
Columns: year
starts
wins
top_5
top_10
poles
avg_start
avg_finish
winnings
position
team_s

Question: How many times did the team with an average start of 18.9 make the top 10?
SQL: SELECT SUM("top_10") FROM nascar_driver_stats_2 WHERE "avg_start" = 18.9