Are there good statistics on the percentage of technical people on salary or hourly, versus equity-only or piecework? I've read a number of times that the gene

Are there good statistics on the percentage of technical people on salary or hourly, versus equity-only or piecework? I've read a number of times that the general trend in creative work is that salaries take a far lesser morale toll than bonuses or piecework. Anecdotally, open source seems to have accepted contributors on salary far more often than piecework, like patch bounties.