How accurate are voter turnout numbers?

This should be a tweet, but I couldn't get it down to 140. Real blog posts coming later.

My sister and I both received voter registration cards at our parents' address. Neither of us has lived there in years. I've never even been eligible to vote municipally there (i.e. there were no municipal elections between my 18th birthday and the day I moved out).

Therefore, official statistics show voter turnout at my parents' address as 50%. In reality it was 100% - both my parents voted, and my sister and I both voted in our respective cities.

In addition to the voter card I received at my parents' address, I also received one at my own address and used it to vote here in Toronto. Therefore, official statistics show my own personal voter turnout as 50%, whereas in reality it was 100%.

This causes me to question whether low voter turnout numbers are really as low as they seem.