Party (round) all the time?
aaronkharris.com
aaronkharris.com
I did a party round, mainly because we could do it in a fraction of the time it would take to get a lead. And we did have a couple deep pockets come in. It worked out for us, but I could see it going the other way. Would love to dig in more.
My guess is that sometimes Techcrunch lists more than 10 "notable" investors in the announcement and somebody puts that into Crunchbase, but other times Techcrunch lists a smaller number. Either way, whatever Techcrunch reports is probably unrelated to how many different investors there were.
A better source would be a survey sent to YC companies, or perhaps data from some internal YC database. That will have its own sampling issues, but the accuracy will be leaps and bounds above Crunchbase.
I assume this is because party rounds have never been more than 3.7% of total rounds, so showing them on the same scale would have left the party rounds line rather hard to glean anything from.
A better approach would probably have been to express the counts as ratios to their 2005 values; they could then have been presented on the same scale.