Notes on how to use the Population Pyramid website

Here are the cohort number for each gender and the total of the sexes from all the cohorts from 99 down. (The 100+ does not register at 0.1% for either males or females.) The cohorts in bold are the ones where the percentage is greater than the next youngest five year cohort.  If the birth rate about the same, you would expect that death rates would mean there would be less people in the 50-54 cohort than in the 45-49 group. In the United States, there was the big baby boom from 1945 through 1965. The last gasp of that increased birth rate is the reason the 50-54 cohort counts as a mode. We also had a smaller baby boom that ended in the past five years, the reason why the ages from 5-9 and 20-24 all count as modes. 

Cohort Male Female Total
95-99  0.0%  0.1%  0.1%
90-94  0.2%  0.4%  0.6%
85-89  0.5%  0.7%  1.2%
80-84  0.8%  1.1%  1.9%
75-79  1.2%  1.4%  2.6%
70-74  1.7%  2.0%  3.7%
65-69  2.4%  2.7%  5.1%
60-64  2.9%  3.1%  6.0%
55-59  3.4%  3.5%  6.9%
50-54  3.5%  3.5%  7.0%
45-49  3.2%  3.1%  6.3%
40-44  3.2%  3.2%  6.4%
35-39  3.1%  3.1%  6.2%
30-34  3.4%  3.5%  6.9%
25-29  3.5%  3.4%  6.9%
20-24  3.7%  3.5%  7.2%
15-19  3.3%  3.1%  6.4%
10-14  3.3%  3.1%  6.4%
05-09  3.3%  3.1%  6.4%
00-04  3.1%  3.0%  6.1%