In Portugal, 32% of the adult population have at least an upper secondary degree. In the Czech Republic, 92% have one.
The data is for 2010 and is provided by EUROSTAT (and is discussed here).
I have graphed the figures for the European countries in the map below. An interesting pattern emerges with the Northern and the East European countries having the highest percentages. But I wonder to what extent these numbers represents real failures/successes of the secondary educational systems rather than different ways of setting up (and naming) the secondary education levels.
click to enlarge. The link to the map is here.
eurosearch 
This is not necessarily linked to the performance of the education systems. On the one hand, the results for CEE are “distorted” by the legacy from the communits times, when everyone had to obtain a degree. Now the rate of dropouts is changing dramatically!
On the other hand, a certificate for degree does not necessarty mean quality – appropriate skills and knowledge. In this regards both UK (who are worried about thier results) and Spain (given as example) perform better than the Czech Republic. Details here
Click to access 48852548.pdf
or here
Click to access report_en.pdf