Maybe 5%:
- 30% cleaning (since others help)
- 10% data exploration (maybe 5% using visualization)
- 20% writing core code
- 30% iterating on the model
- 10% debugging
(I'm an economist, not a data scientist, fwiw; and I'm not making front-end stuff, only doing visualization for internal use.)
By the way, you could edit your post to contain a poll -- click the gear above the editing window and click "Build Poll". (Example here.)