TIMMS 2011 - Portugal's Maths learning raising scores (those were the days)

The five East Asian countries had the largest percentages of fourth grade students (30–43%) reach the TIMSS 2011 Advanced International Benchmark. Building  on this head start, these five countries pulled away from the rest of the world by  a considerable margin at the eighth grade, with by far the largest percentages of students reaching this benchmark—nearly half (47–49%) in Chinese Taipei, Singapore, and Korea. 

Remarkably, nine countries raised achievement across their entire fourth grade student distribution, from low to high performers, improving across all four international benchmarks over the past decade; only one declined across all four benchmarks. At the eighth grade, only three countries showed improvement across all benchmarks, and three had declines.

Ler+:
http://timss.bc.edu/timss2011/downloads/T11_IR_M_Chapter2.pdf