Distributions of properties for small-scale flux ropes at different radial distances. (a) Duration with 25 minutes as bin size. (b) Scale size with 0.0025 au as bin size. (c) The waiting time with 5 minutes as bin size. (d) The wall-to-wall time with 5 minutes as bin size. The blue crosses represent results from the ACE spacecraft whereas the red dots are from the Ulysses spacecraft. Exponential fitting curves and power-law function fitting curves are drawn in (c) and (d), respectively, with the corresponding fitting parameters denoted.