  A stable-frequency transmitter with relative radial acceleration to a
receiver will show a change in received frequency over time, known as a "drift
rate''. For a transmission from an exoplanet, we must account for multiple
components of drift rate: the exoplanet's orbit and rotation, the Earth's orbit
and rotation, and other contributions. Understanding the drift rate
distribution produced by exoplanets relative to Earth, can a) help us constrain
the range of drift rates to check in a Search for Extraterrestrial Intelligence
(SETI) project to detect radio technosignatures and b) help us decide validity
of signals-of-interest, as we can compare drifting signals with expected drift
rates from the target star. In this paper, we modeled the drift rate
distribution for $\sim$5300 confirmed exoplanets, using parameters from the
NASA Exoplanet Archive (NEA). We find that confirmed exoplanets have drift
rates such that 99\% of them fall within the $\pm$53 nHz range. This implies a
distribution-informed maximum drift rate $\sim$4 times lower than previous
work. To mitigate the observational biases inherent in the NEA, we also
simulated an exoplanet population built to reduce these biases. The results
suggest that, for a Kepler-like target star without known exoplanets, $\pm$0.44
nHz would be sufficient to account for 99\% of signals. This reduction in
recommended maximum drift rate is partially due to inclination effects and bias
towards short orbital periods in the NEA. These narrowed drift rate maxima will
increase the efficiency of searches and save significant computational effort
in future radio technosignature searches.
