As provable by Question Number 1 the site started to exist almost exactly six years ago.
Everybody who feels like saying something on this occasion, feel free to post an answer.
Happy birthday MO! While we're enjoying all this free cake, maybe we can take a moment to reflect on how (or even whether) MO has grown in the past year.
Out of curiosity, I put together some search links that show the most highly voted questions and answers in each of MO's 6 years of existence.
In parentheses, I include:
(the number of Q or A posted that year with score at least 1 / the total number of Q or A for that year)
(for some reason it seems to be harder to search for posts with score at least 0). These were taken from the numbers of search results, which should be fairly close to the true number of non-deleted Q's or A's.
It's interesting that the number of posted answers seems to be decreasing. At least some of this effect is due to the fact that "big list" questions are no longer as frequently posted or accepted on the site (a good thing, I think).
However, the fraction of questions and answers with score at least 1 seems to be significantly lower in year 6 than in previous years. The absolute number is also a bit lower.
By popular request, the above searches and numbers with CW posts filtered out:
The fraction of CW posts does seem to have been significantly larger in the early years of MO, though it doesn't fully explain the decrease in the average number of answers per question.