Ok, so I have Italian box office data for every SW from 1965-78. I also have spanish box office data for a fair number of SW's as well. My data comes from imdb, and Catalogo Dei Film Italiani, printed by A.G.I.S.
If you want to know how a particular SW faired at the box office please post the name of the movie and I will be happy to look it up for you and post the gross right here. I also have data for not only SW's, but all other Italian films as well.
All results are in Lire, or ESP, now obsolete currency. I've estimated that 1 US dollar is equal to 700 Lire. This is not adjusted for inflation.
I consider any film to gross over 400,000,000 Lire to be a sizable hit (approx. 25-40 percentile of all italian films for that year), while a blockbuster hit would gross over 1000,000,000.
What you need to know: Some results are rather surprising. Some films that did mediocre at the box office have grown in popularity over the years. The Great Silence is an example. Other films were big hits upon its release but have since drowned in obscurity. This may be due to changing tastes over the years, but more often it is due to lack of proper DVD release and television exposure.
Also, keep in mind that this is only for Italian box office data. Italians may well have different taste from Germans, Dutch, Spanish, Finnish, French etc.....
For example all the Gemma films were amazingly successful in Italy. Even his average films grossed more than Django and Sartana in Italy, whereas I believe in Germany his films were not quite as popular.
World wide box office gross probably would give a more accurate depiction on the true success of a movie but I don't have that data. Still, it makes for though provoking discussion.
If anybody can tell me where to find box office data for other countries, especially Germany please let us know.
So ask away!!!