School demographics

I came across some statistics on my school's students today, and thought it was interesting to look at the demographics:


When you take into consideration that there were a similar number of students in grade 6 last year, and almost 300 two years ago, the downward trend in the number of students is pretty clear. As for the sex ratio, according to Wikipedia, "In 2010, the global sex ratio was 986 females per 1,000 males." The sex ratio for this school is 943 females per 1,000 males. Here are female/male sex ratios by grade:
Grade 1: 936 per 1000
Grade 2: 882 per 1000
Grade 3: 1187 per 1000
Grade 4: 859 per 1000
Grade 5: 879 per 1000
Grade 6: 942 per 1000

In the statistics above, you can see that for some reason there were about 15 more students in grade 3, and all of those 15 are girls. Seeing as they were born in 2003, perhaps some of them were conceived during the World Cup...

Of course, this is just one school. I went to a demonstration class in Mok-dong a few weeks ago and eventually realized that there were two boys for every girl in the grade 6 class that was being taught. I asked the teacher about this and she said that was the ratio for grade 6 students at that school (the other grades apparently weren't as bad). Needless to say, 2:1 is a rather skewed ratio, though it was confined to one area (and the school was fairly small).

I was wondering just how much of a change this was from the 1980s and 1990s, and according to this article, "South Korea’s sex ratio rose from just above normal to 117 in 1990—then the highest in the world—before falling back to more natural levels." The 'normal level' is considered 105 males for 100 females, and calculating it that way, the sex ratio at my school is 106 males to 100 females, making it only slightly above normal. Well then, looked at that way, the gender imbalance isn't as great as it might first seem.

It would be fascinating to see nationwide statistics over the last decade to see how the low birthrate has been developing. It doesn't seem like a trend that will change any time soon.