Statistics of Langmuir waves detected by TDS. Top: daily number of observed Langmuir waves (monthly averages) as a function of time. The red line shows the rates for all Langmuir waves, blue line only for the waves not associated with a Type III radio burst observed by RPW (“sporadic” Langmuir waves). Middle: total monthly number of sporadic Langmuir waves with the heliocentric distance over-plotted. Bottom: histograms of peak and rms amplitudes of Langmuir waves associated with Type III events (black) and the sporadic ones (blue). By “waves”, in this context, we mean individual TDS snapshots containing detected waves.