After reading a post by user Gopi in the chat room, I wrote a query on Data Explorer which lists the number of questions posted in each month and the number of closed questions among them (although it is not exactly what Gopi asked). I will not try to interpret the data here, but if you find it interesting or if you have something to say about it, let me know.
For the last month in the table, the actual number of questions and closed questions should be larger than the numbers shown in the table because the table is as of the time of the last update of the database.
Questions with no answers, low score, and low activity for a while are deleted automatically. This means that in most cases, closed questions with negative score which are more than 30 days old and closed questions with score 0 which are more than 365 days old will be deleted and not included in the table. Therefore, the actual number and the actual rate of closed questions for more than one month old will be higher than shown in the table.
Warning. I am not familiar with SQL, the language in which this query is written. Therefore, the query may well contain a bug. In case you find a bug, I am happy to learn about it.
Aside. The table shows that there is one question posted in 2008. Unfortunately this is not an evidence for a time machine. This question was migrated from another site, and it was posted in 2008 in the original site. Ideally the query should use the month when the question started to appear on cstheory.stackexchange.com, but I currently ignore this issue because this should affect only the migrated questions and there are not many of them.