Table:
text: Somerset County Cricket Club in 2009
NatWest Pro40
Batting averages
Player Matches Innings Runs Average Strike_rate Highest_score _50s
Wes Durston Category:Articles with hCards 2 2 77 77.00 171.11 57 1
Alfonso Thomas Category:Articles with hCards 4 3 40 40.00 166.66 30* 0
Zander de Bruyn Category:Articles with hCards 4 4 87 29.00 92.55 43* 0
James Hildreth Category:Articles with hCards 4 4 62 15.50 86.11 31 0
Justin Langer Category:Articles with hCards 4 4 47 11.75 83.92 15 0

Question: What is the minimum 50's scored for Somerset County Cricket Club under Natwest Pro40 batting averages in 2009?