Calculate the number of weekends that I have worked

I want to figure out how many weekends I've been working this year (time intervals, filters). How do you do that?
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The database consists of: date, start time, end time and notation.
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Have tried with Pivottable, but there can only figure out the date range different weekdays. Not weekends.
To see if I worked a weekend requires that either or both Saturday and Sunday are written down.