Hi, Out of curiosoty, I've been trying to find out when in the history of economics the concept of active population as a denominator for the unemployment ratio started being used vs the more natural complement to employed to population ratio. As everyone should now, current unemployment data doesn't mean much, eg: at the end of Q4 2004, for male aged 25 to 54, standardized unemployment as measured by OECD was 4.6% in the USA and 7.4% in France. For the same group, the employment to population ratio was 86.3% in the USA and ... 86.7% in France. So 60% higher unemployment together more people working in the group, not really representative of what one could think reading only the unemployment data. Thanks in advance for any help, Laurent GUERBY