Interesting fact of the day, about 78% of the worlds GDP is produced in countries using the metric system. 22% of the worlds GDP is produced by the imperial system (the system the USA and UK and a few other countries use).
Actually a correction, in that measurement the UK was counted as metric.. which is only partly true.. So the number for imperial system is a bit higher in reality.
@freemo , the USA has a weird hybrid system, where officially everything has to be done metric, but then translated to imperial for public consumption.