It's very common to see this in different countries as well. A goverment that may have the highest amount of supportes losing because not enough ticket-splitting, due to logistic issues, corruption or other concerns, also, as the opposite goverment can have more power within the inside goverment and politics, people tend not to vote feeling their goverment has no chance in the elections.
When the same type of goverment has been leading for many years, it's very difficult to really have a change, so the people that really want it, may abstain from voting or migrate to a different country.