Are You Un-fashionably Late?

Here is a histogram of when people showed up to a party. From FiveThirtyEight, begun by Walt Hickey, but then crowdsourced from readers. Of 803 guest times submitted, the median guest arrived almost an hour after the party's start time. Four guests showed up over 3 hours late. How fashionable is that?

They also looked at a scatterplot of arrival time against number of party guests.  They fit a regression, with only a 5%  R², and the following interpretation: as host you should expect the mean guest to arrive 42 minutes after the party's start plus 4 minutes for every additional 10 guests. So comparing parties that differed by 10 guests, on average, the guests to the larger party arrived 4 minutes later.