Why is "ten girls on statistics, nine guys"?

Why is "ten girls on statistics, nine guys"? Tell me, you remember the words of this wonderful song?

Today is a holiday with the girls,
Today will be dancing.
And the girls cheeks burn,
On the morning burning red.

Came girls,
They stand on the sidelines
Handkerchiefs in the hands of Teasing.
Because in ten girls
According to statistics, nine guys.

Probably everyone knows, or at least once heard this song.
Wrote her composer Alexander Kolker and poet Kim Ryzhov in 1966.
Maybe someone remembers the time, I still feel the taste of ice-cream in a silver "zolotyanke" for 11 cents.

But hardly anyone thought about why ten girls - Statistics nine guys? And what kind of statistics? You can think about the impact of this imbalance of large losses of our soldiers during the Great Patriotic War, and probably soon after the war, the picture was exactly like that. But it is easy to calculate that 18-20-year-old girls and boys 1966 were born after the war.

Let us look at scientific facts.
Statistically, boys are usually born more. The probability of a boy is a number, somewhat larger than 0,5 (near 0.51), and the girls - less than 0,5 (near 0.49). Why is this happening, why the birth of a boy or girl is not equally likely, and relevant genetic determinants (Mendel's law of segregation by sex)?

Satisfactory answers to these questions has yet been received, is only known that from the moment of conception, the proportion of boys more than the proportion of girls. Boys born by about 5-6% more.

But in this case, our situation is even more confused, it turns out to be more boys than girls. So where did he go ten boy?

Recently, watching news, found an interesting message.
"European scientists studying the proportions in the birth of boys and girls, found that couples who are victims of emotional stress on the eve of conception, are much more likely to reveal the light girl"

Perhaps here lies the answer to our question? And what if the stress produced during the war, broke the genetic laws? The answer could be obtained only by referring to census data.
And here we expected a strong disappointment. It turns out that my grandfather, Stalin was afraid to hold a census immediately after the war, perhaps afraid of opening data about the huge losses among the civilian population. It so happens that the first postwar census was in 1959 during a thaw.

But, as the saying goes: "Necessity is the mother of invention" and "silver lining does not happen.
A little patience, and in front of us report the CSO of the USSR, 1960, "Distribution of total and married population by age and sex according to the All-Union census of 15 January 1959 (Volume 1) (Russian Federation).

The first thing that catches the eye - women really more. If the men in 1959 were 52,425 thousand people, the women - 65,110 thousand people (in other words, ten girls on Statistics eight children.) Did the authors of the song made a mistake in the calculations? No, no, can not be! ..

So what's the matter? Where is the truth? And who is right? ... As the saying goes, "a good idea comes afterward." Remember lyrics - "The girls came ..." So what's the matter, the song says about girls, but we take the statistics of the population, from infants to 100-year-old men.

We assume that our "dancing" in 1966 came to girls aged 10 to 30 years, then in the 1959 census they will be from 3 to 23 years. Again we turn to materials CSB USSR, 1960, and by simple calculations we obtain:
The girls who came to dance in the 60's of last century, it was 20,527 thousand people, and children - 20,915 thousand people. That is - virtually the same, and any genetic changes to our population did not happen ...

And therefore the song should sound like this: