Define a period

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How many working days in year 1991?

Here is the detail of the calculation:

Because 1991 is not a leap year, it has 365 days.

Let's remove 52 saturdays and 52 sundays. It remains 261 days.

Now, let's remove 9 public holidays that do not fall during a weekend and we obtain 252 working days in 1991.

Here is the list of these 9 public holidays:

1. Nieuwjaarsdag : Tuesday, 1 January, 1991
2. Paasmaandag : Monday, 1 April, 1991
3. Dag van de Arbeid : Wednesday, 1 May, 1991
4. Hemelvaartsdag : Thursday, 9 May, 1991
5. Pinkstermaandag : Monday, 20 May, 1991
6. Onze-Lieve-Vrouw Hemelvaart : Thursday, 15 August, 1991
7. Allerheiligen : Friday, 1 November, 1991
8. Wapenstilstand : Monday, 11 November, 1991
9. Kerstmis : Wednesday, 25 December, 1991

And here is the public holiday falling on a weekend:

1. Nationale Feestdag : Sunday, 21 July, 1991