weeds	yield
0	166.7
0	172.2
0	165.0
0	176.9
1	166.2
1	157.3
1	166.7
1	161.1
3	158.6
3	176.4
3	153.1
3	156.0
9	162.8
9	142.4
9	162.7
9	162.4