Revisit the fraction of radio-loud narrow line Seyfert 1 galaxies with
  LoTSS DR1
  Radio-Loud narrow-line Seyfert 1 galaxies (NLS1s), especially the extremely
radio-loud ones, are widely accepted as the jetted versions of NLS1s. We
explore the radio-loud fraction for NLS1s with recently released LoTSS DR1 at
150 MHz. The radio detection rate is about 28\% for LoTSS DR1. The radio
detected NLS1s have lower redshift than the non-detected ones. Moreover, the
150 MHz radio luminosity of NLS1s detected by LoTSS are about two orders of
magnitude weaker than that of the previous samples. By defining the radio
loudness with the ratio between 150 MHz radio flux and SDSS \textit{r} band
flux, the radio-loud fraction is about 1\% with the critical radio loudness
equalling to 100. Radio loudness shows no dependence on central black hole
mass, while weak correlations are found between radio loudness and disk
luminosity, as well as Eddington ratio.
