Breeding-population Index (millions) 
Figure 2. 
70 
60 
50 
40 
30 
20 
10 

1953 
Trends in Breeding-population Indexes 
by Management Units, 1953-1962 
y Pu ‘A 
CENTRAL ra ‘A 
*. # 
Pa ne ~o" “A 
o” ~ —o” “Se 
on 
oo by 
r 
¢ 
rd 
@ 
7 
é 
WESTERN 
1954 1955 1956 1957 1958 1959 1960 1961 1962 
-6- 
