A quick analysis of the trends in the number of weddings in France (1975–2010)

I’m currently planning my wedding, and my fiancée and I were discussing wether there were more or less couples getting married over time. It turns out that this information is quite easy to get via INSEE, a french institute that deals with all demographic and economic questions. Additionally, they provide a csv file with monthly data, so we can look at the intra-annual trends.

The short answer is: the number of celebrated weddings decreased since 1975, although there seem to be some kind of stabilization since 1985.

What is interesting is that the monthly trend seems to be less clear:

While some months like Oct. to Apr. consistently decreased over time, the summer time seem less easily predictable. Looking at the data for only May to Sep. (including Oct. as a reference) makes it clear that these months show both a long term and short term (~5 years) fluctuations:

Moreover, it seems that if at year n, there were a high number of weddings in june, there will by a high number of weddings in july at year n+1 (but this is not significant).

So, if any reader has an interesting hypothesis about why some years decline but some other fluctuate, I would be really glad to know!

Edit (Aug. 19, 2010) : Baptiste Coulmont offers the solution to the 5-years fluctuation  (in french): as it turns out, when there are 5 saturdays in a month, it has more weddings than the years around it. Which makes complete sense.