Complex sentence: Therefore, a country as large as Sweden with only 9 million citizen, could have a much higher suicide rate than Poland if Sweden had 38 million citizen instead of 9 million, since people in Poland have a stronger social bond than people in Sweden.
Split into simpler sentences: Therefore, a country as large as Sweden with only 9 million citizen, could have a much higher suicide rate than Poland if Sweden had 38 million citizen instead of 9 million. Especially since people in Poland have a stronger social bond than people in Sweden.