250 
Distribution of Fertility 
and that for the same age at marriage it decreases with its duration. Thus 
of women who married at age under 20, and whose duration of marriage was 
10 years and upwards, 3 21 per cent, were barren; of those whose duration was 
15 years and upwards, 2-59 per cent., whilst for a duration of 20 years and 
upwards the percentage was only 2-4:3. These differences are I think really due 
to first births occurring from 10 to 15 and from 15 to 20 years after marriage, 
rather than to increased restraint in the more modern marriages, for on reference 
to the "Vital Statistics" of New South Wales for the 10 years 1893—1902, 
I find that the average annual first births from 10 to 15 years after marriage 
were 24, from 15 to 20 years after marriage 5, and from 20 to 25 years '5. 
When the number of marriages and the proportion of those marrying at such 
ages as to be able to bear children at the intervals referred to are considered, 
as also the ruptured marriages caused by the death of husband or wife, there 
is little or nothing left to be accounted for by restraint in the more modern 
marriages. It seems safe to assume then that the naturally sterile women cannot 
exceed 2^ per cent. So far as I am aware these statistics are the first from 
which an accurate determination of the value of this ratio can be made. Again 
referring to Table XIII., it is seen that the condition of things existing after 
the close of the reproductive period is that the average family is 6"I9 children, 
the median 5-88, the mode 7, and that 28'36 per cent, of such women produce 
50 per cent, of the children. If however, the married women at all ages at 
death be taken, it is found that the average family is 5'31 children, the median 
4'55, and that 25'(J1 per cent, of the women produce 50 per cent, of the children. 
This latter result — based on what I regard as the trL,e method, being on 
deaths at all ages — is almost in exact accordance with Prof Pearson's conclusion 
from the Anglo-Saxon and Danish statistics, viz. " that one quarter of the popula- 
TABLE XV. 
Distribution of Fertility. Duration of Marriage 15 years and upwards. 
Experience of New South Wales Census 1901. 
Families 
Families 
Families 
Size of 
Size of 
Size of 
Family 
Family 
Family 
Number 
Per Cent. 
i 
Number 
Per Cent. 
Number 
Per Cent. 
0 
5074 
5-563 
,9 
8420 
9-231 
18 
67 
-073 
1 
3309 
3-628 
10 
7260 
7-959 
19 
32 
-035 
2 
4079 
4-472 
11 
5076 
5-565 
20 
10 
•Oil 
3 
5416 
5-938 
12 
3550 
3-892 
21 
9 
■010 
h 
6909 
7-575 
13 
2078 
2-278 
22 
4 
•004 
5 
8273 
9-070 
U 
1171 
1-284 
23 
3 
•003 
6 
9551 
10-471 
15 
591 
-648 
26 
1 
•001 
7 
8 
10022 
10-987 
16 
283 
-310 
9907 
10-861 
17 
119 
•131 
Totals 
91214 
100-000 
