Graph 1  At the same time as there has been above-average employment growth, the participation rate has increased and is now close to its record high. Movements in the participation rate have been highly correlated with employment growth for some time (though this doesn't have to be the case).
I will invoke Chris Caton in noting that you should always avoid statements like: if the participation rate hadn't increased, the unemployment rate would have been lower. Both the rise in the participation rate and the lower unemployment rate increase labour utilisation and reduce the amount of spare capacity in the labour market.