Only 6% of Portuguese family declares earnings over €50Ks annually. Those 6% of Portuguese families (that are thus premised to be "rich", while most of them are just middle class, period), pay 53% of the whole collected "individual earnings tax" (IRS). 42% of the total number of families doesn't pay any IRS.
This is a reflection from António Nogueira Leite, and is worth to keep on our head every time we discuss Portuguese society and taxation.