Estimating overcrowding with the HSL Realtime API

Have you ever hopped on to tram number 7 just to discover it's packed with people going in and out of Länsisatama? Ugh, what ever happened to having an entire tram section for yourself? Luckily for us, HSL has a top-notch API for real-time vehicle tracking. We can use it to guesstimate how crowded the trams are, by looking at stop times over the duration of the trip.