Figure 4: Relative Frequencies by Classification (Sampling Quotas)

Decade    Total   Named+     Named+     Unnamed+   Unnamed+
                  Internal   External   Internal   External
Bliley      7          6          0          1          0
19xx        5          0          0          5          0
1950        6          2          0          2          2
1960       16          8          1          6          1
1970       36         13          2         21          0
1980       71         38          1         32          0
1990       61         21          0         40          0
Total     202         88          4        107          3