Singaporean students generally perform very well in international tests of mathematics and science. Nonetheless, in multi-cultural Singapore, there exist gaps with the Malays, a minority group in Singapore, systematically lagging behind the other ethnic groups of the Chinese and Indians in many educational performance indicators. While there have been previous qualitative assessments of this issue, rigorous statistical analyses are lacking. In this article, I analyse data from 1991 to 2011 of aggregate percentage passes in national examinations for the different ethnic groups in Singapore. Using time series techniques and regression, I uncovered two major findings. First, the Malay trends in percentage passes for the last two decades were strongly correlated with the non-Malay, national trends. Second, despite the correlation, there remained fluctuations around the national trend by Malay cohorts in the past two decades. Malay cohorts tended to perform better during an upward national trend, but also performed worse during a downward national trend, indicating systematic volatility in performance. The implications of these findings are discussed in the light of current research on educational gaps and three decades of community self-help to improve the educational achievement of the minority Malays in Singapore.