I have seen an example about "on par with sth" on Cambridge Dictionary:

"At this rate, they'll have 600,000 visitors to the exhibition, which will put it on a par with the Van Gogh exhibition."

However, I dont wonder the whole meaning of sentence. In this context, I has been confused by the word "which". I didn't get it complements for which noun here. But surely, it cannot provide information for "the exibition" because of its unproper meaning.

So, what does "which" complement for in this case? Besides, can "which" complement for the preceeding clause? I'm very doubt about this case, because if I comprehend this meaning in this way, it seems to be quite proper.

Thanks!