The collision strengths, (a) Ω_{1 → 2}, (b) Ω_{1 → 3} and (c) Ω_{2 → 3} presented as a function of electron energy in eV. Also presented are the corresponding effective collision strengths as a function of temperature in K. Solid black lines with stars are the current data set and the dashed line with crosses represent the results from Storey & Sochi (2016).