I am curious (actually I wanted to say I wonder...) if a sentence that starts with "I wonder...", "We are wondering...", "They were wondering...", and so on should end in a period or a question mark?
I noticed that some here in the NG end their sentences in periods although it sounds like they were asking something. But I also saw others that end in a question mark.
I wonder how it should be ended... (now I use ellipsis to be safe)

Thanks a lot in advance!