Population
Five year age groups
About this topic
Five year age groups show the population in standard five-year cohorts from early childhood through older age. Because each band covers the same span of years, the topic gives a clear and comparable view of an area's age structure.
This topic is useful for identifying growth or decline in specific cohorts and for comparing age patterns across places and over time. For service planning, it is often read together with service age groups, household types, and dwelling types.
Interpretation notes
- Age is reported as at Census night, so the counts are a snapshot of the resident age structure at that point in time.
- Because each band covers the same five-year span, this topic is best for exact cohort comparison rather than service-planning life stages.
Related topics
Key insight
In 2021, 50 to 54 year olds was the largest age group among residents in Black Rock (Vic.), accounting for 8.7% (554 people). This share was higher than Bayside (C) (8.3%). Since 2016, the biggest change was in 25 to 29 year olds, which decreased by 712 people and 3.6 percentage points.
Section overview
Age structure - Five year age groups
Black Rock (Vic.) - Total persons (Usual residence)
This table summarises five year age groups for Black Rock (Vic.) in 2021 for persons, with comparison against Bayside (C) and change since 2016.
Age structure - Five year age groups snapshot
2021 distribution by category for Black Rock (Vic.), with comparison markers for Bayside (C).
0 to 4
2021 count
249
% of total
3.9%
Change from 2016
-1.3pp
249
3.9%
-1.3pp
5 to 9
2021 count
336
% of total
5.3%
Change from 2016
-0.7pp
336
5.3%
-0.7pp
10 to 14
2021 count
428
% of total
6.7%
Change from 2016
+0.4pp
428
6.7%
+0.4pp
15 to 19
2021 count
463
% of total
7.2%
Change from 2016
+1.0pp
463
7.2%
+1.0pp
20 to 24
2021 count
281
% of total
4.4%
Change from 2016
-2.4pp
281
4.4%
-2.4pp
25 to 29
2021 count
172
% of total
2.7%
Change from 2016
-3.6pp
172
2.7%
-3.6pp
30 to 34
2021 count
219
% of total
3.4%
Change from 2016
-2.6pp
219
3.4%
-2.6pp
35 to 39
2021 count
256
% of total
4.0%
Change from 2016
-2.3pp
256
4.0%
-2.3pp
40 to 44
2021 count
378
% of total
5.9%
Change from 2016
-1.4pp
378
5.9%
-1.4pp
45 to 49
2021 count
444
% of total
6.9%
Change from 2016
-0.4pp
444
6.9%
-0.4pp
50 to 54
2021 count
554
% of total
8.7%
Change from 2016
+1.9pp
554
8.7%
+1.9pp
55 to 59
2021 count
503
% of total
7.9%
Change from 2016
+1.6pp
503
7.9%
+1.6pp
60 to 64
2021 count
483
% of total
7.6%
Change from 2016
+2.9pp
483
7.6%
+2.9pp
65 to 69
2021 count
456
% of total
7.1%
Change from 2016
+2.3pp
456
7.1%
+2.3pp
70 to 74
2021 count
439
% of total
6.9%
Change from 2016
+3.3pp
439
6.9%
+3.3pp
75 to 79
2021 count
326
% of total
5.1%
Change from 2016
+2.2pp
326
5.1%
+2.2pp
80 to 84
2021 count
177
% of total
2.8%
Change from 2016
-0.2pp
177
2.8%
-0.2pp
85 and over
2021 count
210
% of total
3.3%
Change from 2016
-0.8pp
210
3.3%
-0.8pp
Chart view
Age structure - Five year age groups change
Absolute change in category counts between 2016 and 2021.
0 to 4
-469
-1.3pp
5 to 9
-501
-0.7pp
10 to 14
-447
+0.4pp
15 to 19
-403
+1.0pp
20 to 24
-660
-2.4pp
25 to 29
-712
-3.6pp
30 to 34
-624
-2.6pp
35 to 39
-623
-2.3pp
40 to 44
-637
-1.4pp
45 to 49
-571
-0.4pp
50 to 54
-400
+1.9pp
55 to 59
-381
+1.6pp
60 to 64
-179
+2.9pp
65 to 69
-211
+2.3pp
70 to 74
-65
+3.3pp
75 to 79
-73
+2.2pp
80 to 84
-237
-0.2pp
85 and over
-365
-0.8pp
Data table
Five year age groups for Black Rock (Vic.). Age structure - Five year age groups. 2021 and 2016 counts, percentages, and change compared with Bayside (C).
| Category | 2021 | 2016 | Change | |||||
|---|---|---|---|---|---|---|---|---|
| Count | % | Bayside (C)% | Count | % | Bayside (C)% | Count | pp | |
| 0 to 4 | 249 | 3.9% | 4.4% | 718 | 5.2% | 5.1% | -469 | -1.3pp |
| 5 to 9 | 336 | 5.3% | 5.8% | 837 | 6.0% | 6.8% | -501 | -0.7pp |
| 10 to 14 | 428 | 6.7% | 7.2% | 875 | 6.3% | 7.1% | -447 | +0.4pp |
| 15 to 19 | 463 | 7.2% | 6.9% | 866 | 6.2% | 6.4% | -403 | +1.0pp |
| 20 to 24 | 281 | 4.4% | 5.1% | 941 | 6.8% | 5.1% | -660 | -2.4pp |
| 25 to 29 | 172 | 2.7% | 3.6% | 884 | 6.3% | 3.9% | -712 | -3.6pp |
| 30 to 34 | 219 | 3.4% | 4.2% | 843 | 6.0% | 4.3% | -624 | -2.6pp |
| 35 to 39 | 256 | 4.0% | 5.3% | 879 | 6.3% | 5.4% | -623 | -2.3pp |
| 40 to 44 | 378 | 5.9% | 6.3% | 1,015 | 7.3% | 7.4% | -637 | -1.4pp |
| 45 to 49 | 444 | 6.9% | 7.7% | 1,015 | 7.3% | 8.6% | -571 | -0.4pp |
| 50 to 54 | 554 | 8.7% | 8.3% | 954 | 6.8% | 7.8% | -400 | +1.9pp |
| 55 to 59 | 503 | 7.9% | 7.3% | 884 | 6.3% | 7.1% | -381 | +1.6pp |
| 60 to 64 | 483 | 7.6% | 6.5% | 662 | 4.7% | 5.9% | -179 | +2.9pp |
| 65 to 69 | 456 | 7.1% | 5.6% | 667 | 4.8% | 5.6% | -211 | +2.3pp |
| 70 to 74 | 439 | 6.9% | 5.4% | 504 | 3.6% | 4.4% | -65 | +3.3pp |
| 75 to 79 | 326 | 5.1% | 4.1% | 399 | 2.9% | 3.1% | -73 | +2.2pp |
| 80 to 84 | 177 | 2.8% | 2.7% | 414 | 3.0% | 2.4% | -237 | -0.2pp |
| 85 and over | 210 | 3.3% | 3.4% | 575 | 4.1% | 3.7% | -365 | -0.8pp |
| Total | 6,389 | 100.0% | 100.0% | 13,940 | 100.0% | 100.0% | -7,551 | 0.0pp |