The general trend upwards is interesting, but is anyone else more intrigued by the dip in 2008 followed by the spike in 2010? My hypothesis is that this is bei

The general trend upwards is interesting, but is anyone else more intrigued by the dip in 2008 followed by the spike in 2010? My hypothesis is that this is being heavily influenced by automated emails from certain websites that the author is using over time. And this could explain the general trend; that proportionally hand-written emails make up a smaller portion of our messages these days -- a quick glance at my inbox and automated 'notifications' are generally more likely to have longer subject lines.