Story 2129: Microstock Sales: Top iStock Earners Published: 10/7/2009   For most of this year I have been tracking the number of downloads for 117 of the 150 most productive contributors on iStock. (I have been unable to identify the other 33 in the top 150.) Total downloads of the 117 during the last seven months represent about 17% of all iStock contributor downloads. Sixty-five of the 117 contributors have seen a slight decline in average downloads-per-month since March.